Peppermint Essential Oil Benefits: Uses, Safety & What Research Really Says

Peppermint essential oil benefits are often talked about in wellness circles, but not every popular claim is supported by the same level of research. With its crisp, cooling aroma and refreshing character, peppermint has become one of the most widely used essential oils in aromatherapy, personal care and everyday wellness.

But what are the real peppermint essential oil benefits — and which popular uses are actually supported by research?

Peppermint oil has been studied for several purposes, with some of the strongest evidence involving specially formulated peppermint-oil products for digestive symptoms such as irritable bowel syndrome (IBS). Other uses, including topical application for certain headaches and inhalation for nausea in specific settings, have also been studied, although the evidence is more limited. Many other familiar uses remain rooted largely in traditional practice, aromatherapy or personal preference rather than strong clinical evidence.

In this guide, we’ll explore what peppermint essential oil is, what the research says about its potential benefits, popular ways to use it, important safety considerations and how peppermint essential oil differs from peppermint extract and peppermint tea.

Essential Oils for Beginners: A Simple Guide to Getting Started Safely

LISH editorial note: Essential oils are highly concentrated. Natural does not automatically mean risk-free, and the safest way to use peppermint oil depends on the product, method of use, age, health status and other individual factors.

What Is Peppermint Essential Oil?

Peppermint essential oil comes from Mentha × piperita, a naturally occurring cross between water mint and spearmint. The concentrated oil is obtained from the leaves and flowering parts of the peppermint plant and contains the aromatic compounds responsible for peppermint’s distinctive cooling scent and flavour.

Two of its best-known constituents are menthol and menthone. Menthol is particularly associated with peppermint’s characteristic cooling sensation, which helps explain why peppermint oil appears in a wide range of personal-care, topical and aromatic products.

It is important, however, to distinguish peppermint essential oil from peppermint tea, peppermint leaf and peppermint extract. Essential oils are highly concentrated preparations, and a method of use that is appropriate for peppermint tea or a formulated food product should not automatically be assumed to be appropriate for concentrated essential oil. NCCIH likewise discusses peppermint leaf and peppermint essential oil as different preparations with different evidence and safety considerations.

This distinction is especially important because the strongest evidence we have for IBS involves enteric-coated peppermint-oil capsules, not someone adding drops of essential oil to water. NCCIH reports modest short-term benefits for several IBS symptoms, while the 2022 systematic review found peppermint oil performed better than placebo overall but also produced more adverse effects and rated the certainty of evidence very low.

Peppermint Essential Oil Benefits: What Does the Research Say?

Peppermint essential oil has a long history of traditional use, but not every popular claim about it is backed by the same level of research. Some uses have been studied much more closely than others, while many remain rooted in traditional wellness practices or personal experience.

So, what does the evidence actually tell us? Let’s look at some of the most talked-about peppermint essential oil benefits — and where the research is strongest.

1. May Help Ease Some IBS Symptoms

Peppermint oil is probably best known in research for its digestive benefits, particularly for people with irritable bowel syndrome (IBS).

Studies have found that certain enteric-coated peppermint oil capsules may help ease symptoms such as abdominal pain, bloating and gas. A 2022 review of 10 randomized trials involving more than 1,000 people found that peppermint oil performed better than placebo for overall IBS symptoms and abdominal pain, although side effects were more common and the overall quality of the evidence was considered low.

That distinction matters. The research involves specially formulated peppermint oil capsules, not drops of concentrated essential oil taken at home.

Peppermint oil can also cause side effects such as heartburn, nausea or digestive discomfort in some people, so anyone considering it for IBS or another digestive condition should speak with a healthcare professional first.

2. May Help Relieve Tension-Type Headaches

Peppermint oil is often associated with headaches, but the research is more specific than many wellness articles suggest. The best evidence involves topical peppermint oil preparations for tension-type headaches, rather than migraines or headaches in general.

In one randomized, placebo-controlled study, a 10% peppermint oil preparation applied to the forehead and temples reduced the intensity of tension-type headaches compared with placebo. The European Medicines Agency also recognizes certain peppermint oil preparations applied to the forehead and temples for the relief of mild headaches.

Peppermint’s cooling effect comes largely from menthol, which stimulates cold-sensitive receptors in the skin. That cooling sensation may be part of the reason topical peppermint preparations can feel soothing during a tension headache.

Still, this doesn’t mean that every peppermint essential oil product should be applied directly to the temples. Concentration and formulation matter, and essential oils can irritate the skin. If you’re using a peppermint product topically, follow its directions carefully and avoid getting it near the eyes.

I like this version because it gives readers something genuinely useful without making the much broader claim that peppermint oil “treats migraines.”

3. May Offer Cooling Comfort for Sore Muscles

That unmistakable cooling feeling is one of peppermint oil’s most appealing qualities. Menthol, one of its main natural components, activates cold-sensitive receptors in the skin, creating the refreshing sensation that makes peppermint a popular ingredient in massage oils, balms and other topical products.

Peppermint oil also has a long history of topical use for localized muscle discomfort. The European Medicines Agency recognizes this as a traditional use, meaning there is a long record of use but not enough strong clinical-trial evidence to say that peppermint oil has been proven to treat muscle pain.

For everyday self-care, a properly formulated or diluted peppermint product may feel soothing after a long day or strenuous activity. Just remember that the cooling sensation itself doesn’t necessarily mean the oil is treating the underlying cause of soreness or pain.

Because concentrated peppermint essential oil can irritate the skin, it should be used according to product directions and diluted appropriately with a carrier oil when needed. Avoid broken or irritated skin, and stop using it if redness, burning or irritation develops

4. Its Fresh Aroma Can Feel Refreshing During Cold Season

There’s something instantly refreshing about peppermint’s cool, minty aroma — especially when you’re feeling stuffy or under the weather. That familiar sensation is one reason peppermint appears so often in chest rubs, inhalation products and cold-season wellness routines.

When inhaled, peppermint’s menthol-rich aroma can create a cooling sensation that may make breathing feel fresher or more comfortable. That’s different, however, from actually treating nasal congestion or a respiratory illness.

Peppermint essential oil should not be presented as a treatment for conditions such as asthma, bronchitis, colds or the flu. For everyday aromatic use, some people simply enjoy diffusing peppermint for its crisp scent and the refreshing atmosphere it creates.

If you do use peppermint oil in a diffuser, follow the manufacturer’s directions, use it in a well-ventilated space and be mindful of others in the home who may be sensitive to strong aromas.

5. Its Aroma May Help You Feel More Alert

Peppermint’s bright, cooling scent is one reason people often reach for it when they want to feel refreshed or mentally switched on.

Some small human studies have found that peppermint aroma may influence alertness, attention and certain aspects of cognitive performance. For example, one study found increased subjective alertness and some improvements in memory after exposure to peppermint aroma. Another found better performance on certain clerical tasks when peppermint odor was present.

That said, the research is still limited and not consistent enough to say peppermint essential oil reliably “boosts energy” or improves concentration for everyone. A 2025 scoping review found substantial differences in how studies were designed and measured, which makes broad conclusions difficult.

For everyday use, it is more accurate to think of peppermint as a fresh, stimulating aroma that some people find energizing, rather than as a proven treatment for fatigue or poor concentration.

6. Popular in Oral-Care Products for Its Fresh, Minty Character

Peppermint and mint flavours are closely associated with that clean, fresh feeling we expect from toothpaste, mouthwash and breath-care products. Peppermint essential oil and menthol are therefore commonly used as ingredients in professionally formulated oral-care products.

Research has also found that some essential-oil-containing mouthrinses can help reduce plaque and gingivitis when used alongside regular oral hygiene. However, these studies involve carefully formulated products containing specific combinations and concentrations of essential oils — not peppermint essential oil used on its own.

That distinction is important. While peppermint may contribute flavour and freshness, there isn’t enough evidence to say that peppermint essential oil by itself treats gum disease or provides the same benefits as a tested antimicrobial mouthrinse. NCCIH notes that most peppermint-oil research has focused on other uses, particularly IBS, and that there isn’t enough evidence to draw conclusions about many additional health claims.

For everyday oral care, stick with products that are specifically formulated and labelled for use in the mouth rather than adding concentrated peppermint essential oil directly to toothpaste or homemade mouthwash.

7. May Feel Calming in Certain Situations

Peppermint is usually thought of as bright and refreshing, but its aroma may also feel calming in certain situations. Some clinical studies have found reductions in anxiety after people inhaled peppermint essential oil, although the research has largely been conducted in specific medical settings rather than in people experiencing everyday stress.

For example, a randomized study involving patients with acute coronary syndrome found lower anxiety after peppermint aromatherapy compared with a control group. Another study involving patients recovering from lumbar disc surgery also reported lower anxiety after peppermint oil inhalation.

These findings are interesting, but they don’t yet establish peppermint essential oil as a treatment for anxiety or chronic stress. NCCIH notes that there still isn’t enough evidence to draw conclusions about many of peppermint oil’s proposed health uses.

For everyday wellness, it may be more helpful to think of peppermint as a refreshing aroma that some people enjoy when they want to reset, recharge or create a more uplifting atmosphere.

How to Use Peppermint Essential Oil

Peppermint essential oil is versatile, but because it is highly concentrated, how you use it matters. The best method depends on what you’re hoping to get from it — whether that’s enjoying its fresh aroma, adding it to a self-care routine or using a properly formulated topical product.

Here are some of the most common ways to enjoy peppermint essential oil safely and intentionally.

For Aromatherapy

Peppermint’s crisp, minty aroma makes it a popular choice for diffusers, especially when you want a space to feel fresh and energizing.

Add peppermint essential oil to a diffuser according to the diffuser and essential-oil product directions, and use it in a well-ventilated room. If the aroma starts to feel overwhelming or causes coughing, throat irritation or discomfort, stop using it and get some fresh air. Concentrated menthol vapour can irritate the airways in some people.

Recommended Diffuser: Ceramic Essential Oil Diffuser

LISH Tip: Peppermint has a strong personality. You often don’t need much of it to give a blend that fresh, cooling character.

For Topical Use

Peppermint is also popular in topical products because of the cooling sensation created largely by menthol.

Rather than applying concentrated peppermint essential oil straight to the skin, use a properly formulated product or dilute the oil appropriately in a carrier oil according to product guidance. Peppermint oil can cause redness, rash or irritation in some people, so a patch test is a smart precaution before wider use.

Keep peppermint oil away from the eyes, inside of the nose and other sensitive areas.

In Hair and Scalp Care

That cooling, tingling sensation also explains why peppermint appears in many shampoos, scalp treatments and hair-care products.

For at-home use, choose a hair product that is already formulated with peppermint or use appropriately diluted peppermint essential oil in a carrier oil rather than applying concentrated oil directly to the scalp.

Peppermint may make the scalp feel fresh and invigorated, but we should be careful about claims that it grows hair. Human evidence supporting peppermint essential oil as a proven hair-growth treatment is currently limited, so we’ll present it as a popular scalp-care ingredient rather than a hair-growth remedy.

If hair and scalp care is one of your main interests, you may also enjoy our Rosemary Essential Oil Guide.

In Massage and Body-Care Blends

Peppermint’s cooling character can make it a refreshing addition to massage and body-care products, particularly after exercise or a long day.

Look for a professionally formulated balm, lotion or massage product, or use peppermint essential oil at an appropriate dilution in a carrier oil. The cooling sensation may feel soothing, but remember that feeling relief on the skin is not the same as treating the underlying cause of muscle pain. The EMA recognizes topical peppermint preparations for localized muscle discomfort largely on the basis of traditional use.

In DIY Self-Care Products

Peppermint can also add a fresh, spa-like touch to homemade self-care products such as bath and body blends.

If you’re building your essential-oil supplies from scratch, our Essential Oil Starter Kit for Beginners | What You Need guide can help you choose the basics without overbuying.

But DIY doesn’t mean anything goes. Essential oils are concentrated substances, and products intended for the skin should be formulated with appropriate dilution and used according to reliable safety guidance. If a recipe calls for large amounts of essential oil or suggests putting concentrated peppermint directly on the skin, I would skip it.

Peppermint Essential Oil Safety: What You Should Know

Peppermint essential oil may smell familiar, but it is still a highly concentrated plant oil. A little care goes a long way, especially when you’re using it on the skin, around children or considering a product intended to be taken by mouth.

Here are the main safety points to keep in mind.

Dilute Peppermint Oil Before Using It on Your Skin

Peppermint essential oil can cause skin irritation, redness or a rash in some people. For topical use, choose a properly formulated product or dilute the essential oil appropriately with a carrier oil according to the product directions.

If you’re trying a new topical blend, test it on a small area of skin first and stop using it if you notice burning, persistent redness or irritation.

Keep It Away From Eyes and Sensitive Areas

Anyone who has accidentally gotten mint near their eyes knows just how intense that cooling sensation can become.

Keep peppermint essential oil away from the eyes, inside the nose and other sensitive areas. If you’re using it on the face, scalp or around the temples, follow the directions for the specific product rather than assuming that more oil will give better results. Peppermint oil applied to the skin can cause irritation, and contact with the eyes or mucous membranes can be particularly uncomfortable.

Use Extra Caution Around Babies and Children

Peppermint oil requires special care around young children. NCCIH advises that peppermint oil should not be applied to the face of infants or young children, because inhaled menthol may negatively affect their breathing.

Age recommendations can also differ depending on the product and how it is being used. The EMA, for example, sets different age restrictions for different medicinal peppermint-oil preparations. Rather than using one blanket rule for every product, check the label carefully and speak with a qualified healthcare professional if you are unsure whether a peppermint product is appropriate for a child.

Pregnancy, Breastfeeding and Medical Conditions

If you are pregnant, breastfeeding, managing a health condition or taking medication, it is sensible to check with a healthcare professional before using peppermint oil medicinally.

NCCIH notes that while peppermint in amounts normally found in food is generally considered safe during pregnancy or breastfeeding, much less is known about medicinal amounts.

People considering oral peppermint-oil products should be particularly careful if they have acid reflux or certain digestive, liver, gallbladder or bile-related conditions, since some peppermint-oil preparations may worsen symptoms or may not be appropriate.

Be Careful With Oral Use

This is one of the most important distinctions in the entire guide.

The fact that peppermint oil is used in certain commercially prepared capsules, medicines, foods or flavourings does not mean that concentrated peppermint essential oil should simply be swallowed at home.

Research on digestive benefits has generally involved measured doses in specially formulated products, often enteric-coated capsules. Peppermint oil taken orally can also cause side effects including heartburn, nausea and abdominal discomfort.

For that reason, we’re not recommending DIY ingestion of concentrated peppermint essential oil in this guide.

New to essential oils? Our Essential Oils for Beginners: A Simple Guide to Getting Started Safely walks through the basics of choosing, diluting and using essential oils with confidence.

Recommended Peppermint Essentials

If you’re ready to explore peppermint essential oil at home, a few simple tools can make it easier to use thoughtfully. These are the essentials I’d start with for aromatherapy, topical blends and everyday self-care.

🌿 Peppermint Essential Oil
Choose a clearly labelled peppermint essential oil from a reputable brand, with directions for aromatic and topical use.

Recommended Product: GROVE CO. | Organic Peppermint Essential Oil

🥥 Carrier Oil
A carrier oil makes it easier to dilute peppermint essential oil appropriately for massage, scalp care and other topical uses.

Recommended Product: Cliganic Organic Argan Oil

Not sure which one to choose? Read our guide to the Best Carrier Oils for Essential Oils.

✨ Essential Oil Diffuser
A diffuser is one of the simplest ways to enjoy peppermint’s crisp aroma without applying it to your skin.

Recommended Product: Ultrasonic Aromatherapy Diffuser & Air Humidifier

Peppermint Essential Oil vs. Peppermint Extract vs. Peppermint Tea

People often use the words peppermint oil, peppermint extract and peppermint tea as though they mean the same thing, but they are very different products.

Understanding the difference matters — especially when it comes to how each one is used.

Peppermint Essential Oil

Peppermint essential oil is a highly concentrated aromatic oil obtained from the peppermint plant. It contains compounds such as menthol and menthone that give peppermint its distinctive cooling aroma and sensation.

Because it is so concentrated, essential oil requires more care than peppermint tea or culinary peppermint products. A bottle intended for aromatherapy or topical use should not automatically be treated as something that can be swallowed or added to food.

Peppermint Extract

Peppermint extract is most familiar as a culinary flavouring used in baking, desserts and beverages.

Commercial peppermint extracts are formulated specifically for food use and typically contain peppermint flavour compounds in a food-safe liquid base. That makes them very different from a bottle of concentrated essential oil intended for aromatic or topical use.

So if a recipe calls for peppermint extract, don’t simply substitute peppermint essential oil unless the product is specifically labelled and formulated for that purpose.

Peppermint Tea

Peppermint tea is made by steeping peppermint leaves in hot water. It is far less concentrated than peppermint essential oil and is consumed as a beverage rather than used like an essential oil.

Peppermint tea has its own traditional uses and research history, but findings about peppermint tea should not automatically be applied to peppermint essential oil — and vice versa.

Different peppermint products have different concentrations, uses and safety considerations.

If you’re still getting familiar with essential oils, start with our Essential Oils for Beginners: A Simple Guide to Getting Started Safely.

Frequently Asked Questions About Peppermint Essential Oil

What is peppermint essential oil good for?

Peppermint essential oil is used in a variety of ways, from aromatherapy and topical products to specially formulated digestive-health products. The strongest research is around certain enteric-coated peppermint oil capsules for short-term relief of some IBS symptoms. There is also limited evidence for specific topical peppermint preparations for tension-type headaches, while many other popular uses have less research behind them.

For everyday wellness, many people simply enjoy peppermint for its fresh aroma, cooling sensation and versatility in personal-care products.

Can you put peppermint essential oil directly on your skin?

Peppermint oil can irritate the skin, so don’t assume that concentrated essential oil is appropriate for direct application. Follow the directions on the specific product you are using, and for DIY topical use, use an appropriately diluted preparation rather than casually applying concentrated oil. NCCIH notes that topical peppermint oil can cause rash and irritation.

Need help choosing a carrier oil? See our Best Carrier Oils for Essential Oils guide.

Can you inhale peppermint essential oil?

Peppermint essential oil is commonly used for aromatherapy, including in diffusers. NCCIH considers inhaled peppermint oil possibly safe when used for aromatherapy, although research on inhalation safety is still limited.

Follow the directions for your diffuser and oil, use it in a well-ventilated area and stop if the aroma causes irritation or discomfort.

Does peppermint oil help headaches?

There is some evidence that specific topical peppermint oil preparations may help relieve tension-type headaches. The EMA recognizes certain peppermint oil preparations applied to the forehead and temples for mild headache relief, while NCCIH describes the available evidence as limited.

That doesn’t mean peppermint oil has been proven to treat every kind of headache or migraine.

Can peppermint oil help with IBS?

Certain enteric-coated peppermint oil capsules may provide modest short-term relief from IBS symptoms, including abdominal pain, bloating and gas. The evidence is promising but not definitive, and long-term effectiveness has not been established.

This research involves specially formulated oral products — not swallowing concentrated essential oil from an aromatherapy bottle.

Is peppermint essential oil good for hair?

Peppermint oil is popular in scalp and hair-care products because of its cooling sensation, but claims about hair growth need some perspective.

A frequently cited study found promising hair-growth effects from topical peppermint oil — but the study was conducted in mice, not people. Human clinical evidence showing that peppermint essential oil reliably promotes hair growth is still lacking.

So it makes more sense to think of peppermint as a refreshing scalp-care ingredient than as a proven hair-growth treatment.

Interested in essential oils for hair care? Explore our Rosemary Essential Oil Guide.

Is peppermint essential oil safe for children?

Extra caution is important around children. NCCIH advises that peppermint oil should not be applied to the face of infants or young children because inhaled menthol may negatively affect breathing. The EMA also sets different minimum ages depending on the type of peppermint-oil medicinal preparation and how it is being used.

Because age recommendations vary by product and method of use, check the label and seek professional guidance when you’re unsure.

Can you swallow peppermint essential oil?

Do not assume that a bottle of concentrated peppermint essential oil intended for aromatherapy or topical use is suitable for swallowing.

Clinical research on digestive benefits generally involves carefully formulated oral peppermint-oil products, often enteric-coated capsules. Oral peppermint oil can also cause side effects such as heartburn, nausea and abdominal discomfort.

Use products only for their labelled purpose and speak with a healthcare professional before using peppermint oil medicinally by mouth.

What carrier oils work well with peppermint essential oil?

Jojoba, sweet almond, fractionated coconut and grapeseed oils are all commonly used carrier oils. The best choice depends on whether you’re creating a body oil, massage blend, scalp treatment or another topical product.

Not sure which one is right for you? Explore our Best Carrier Oils for Essential Oils guide.

What essential oils blend well with peppermint?

Peppermint’s bright, minty aroma pairs beautifully with several essential oils. Lavender can soften it, citrus oils can make a blend feel even fresher, while eucalyptus and rosemary complement peppermint’s crisp herbal character.

If you’re experimenting with blends, start with small amounts — peppermint can easily dominate a combination.

Blending Essential Oils: 4 Best Compatible Oils You Will Love for Purification and Relaxation

The Bottom Line

Peppermint essential oil has earned its place as one of the most recognizable and versatile oils in the wellness world. Its crisp aroma, cooling sensation and wide range of uses make it easy to understand why so many people keep a bottle close at hand.

But peppermint is also a good reminder that popular doesn’t always mean proven.

Some of the strongest research involves specially formulated peppermint oil products for IBS, while certain topical preparations have also been studied for tension-type headaches. Other uses — from scalp care and aromatherapy to massage and everyday self-care — may be enjoyable and useful without having the same level of clinical evidence behind them.

The key is to use peppermint thoughtfully: choose products that are appropriate for the way you plan to use them, follow safety directions and remember that concentrated essential oil is very different from peppermint tea, extract or professionally formulated oral products.

Used that way, peppermint essential oil can be a refreshing addition to a well-rounded self-care routine — without asking it to be a miracle cure.

Enjoyed this guide? Keep exploring Life In Style Hub for practical, research-aware essential-oil guides, self-care ideas and everyday wellness inspiration.

Continue Exploring Essential Oils

Ready to learn more? Explore these Life In Style Hub essential-oil guides next:

Essential Oils for Beginners: A Simple Guide to Getting Started Safely
A helpful place to start if you’re new to choosing, diluting and using essential oils.

Rosemary Essential Oil Guide
Discover rosemary essential oil uses, benefits, hair and scalp applications, safety tips and more.

Best Carrier Oils for Essential Oils
Compare popular carrier oils and find the best option for your skin, hair and essential-oil blends.

Essential Oil Starter Kit for Beginners | What You Need
Build a simple starter collection with the oils and accessories you’ll actually use.

Blending Essential Oils: 4 Best Compatible Oils You Will Love for Purification and Relaxation
Learn how to pair essential oils and create more balanced aromatic blends.

References & Resources

The following authoritative resources and published research were consulted in preparing this guide:

National Center for Complementary and Integrative Health (NCCIH). Peppermint Oil: Usefulness and Safety.
This is one of our primary general resources for peppermint-oil evidence and safety.

European Medicines Agency (EMA). Menthae piperitae aetheroleum — Peppermint Oil.
Useful for medicinal uses, traditional-use distinctions, precautions and safety considerations. The EMA page also shows that a periodic review of the peppermint-oil monograph was underway in 2026.

Ingrosso MR, et al. Systematic Review and Meta-analysis: Efficacy of Peppermint Oil in Irritable Bowel Syndrome. Alimentary Pharmacology & Therapeutics. 2022.
The review included 10 randomized controlled trials and 1,030 participants; peppermint oil outperformed placebo on overall IBS symptoms and abdominal pain, although adverse events were more frequent and evidence certainty was very low.

Göbel H, et al. Effectiveness of Oleum Menthae Piperitae and Paracetamol in Therapy of Headache of the Tension Type. 1996.
A randomized placebo-controlled study of a topical 10% peppermint-oil preparation for tension-type headache.

Moss M, et al. Modulation of Cognitive Performance and Mood by Aromas of Peppermint and Ylang-Ylang. International Journal of Neuroscience. 2008.
A human study examining peppermint aroma, cognition, mood and alertness.

Heterogeneity in the Study of Peppermint in Aromatherapy on Cognition and Attention: A Critical Scoping Review. 2025.
Useful for putting the cognition/alertness research into perspective; the review found substantial variation among studies.

Lynch MC, et al. The Effects of Essential Oil Mouthrinses With or Without Alcohol on Plaque and Gingivitis. BMC Oral Health. 2018.
This research involves formulated multi-essential-oil mouthrinses rather than peppermint essential oil alone — an important distinction reflected in our article.

Soleimani M, et al. The Effect of Aromatherapy With Peppermint Essential Oil on Anxiety of Cardiac Patients in Emergency Department. 2022.
A small controlled clinical study conducted in a specific medical population, which is why our article does not generalize the result into a claim that peppermint treats anxiety.