Peppermint Oil Capsules for IBS: Evidence, Capsules, Dosage and Side Effects

What is peppermint oil?

Peppermint oil is extracted from the peppermint plant – a cross between water mint and spearmint. (1) It is used to flavor sweets and beverages and as a fragrance in cosmetic products. Historically, peppermint oil has been used to treat a variety of other conditions such as:

• Stress

• Shingles

• Nausea

• Morning sickness

• Dental plaque. (2, 3)

However, there is too little evidence to know if it is useful for these conditions. Skin preparations containing have also been used for the following conditions, although, there is a lack of clear evidence they are helpful:

• Allergic rash

• Nerve pain

• Itchiness

• Joint pain (4)

Peppermint oil has gained recent popularity as a treatment for irritable bowel syndrome (IBS) and may also help with indigestion and prevent spasms of the GI tract. It is consumed orally in tea or capsule form. (5)

Does peppermint oil help with IBS?

Peppermint oil has been investigated as a treatment for IBS in studies spanning several decades. There is relatively strong evidence that it is effective in improving the overall and specific symptoms of IBS.

The most extensive review peppermint oil included data from over 800 patients from twelve clinical trials. The review showed IBS symptoms were 44% less common in patients who took peppermint oil group compared to those who took a placebo. (6)

In a review by the British Medical Journal, almost 400 IBS patients were assigned either a peppermint oil capsule or a placebo. Those receiving treatment were 2.5 times more likely to improve symptoms than those taking placebo. (7)

Another meta-analysis from 2014 looked at nine studies of over 700 patients and showed peppermint oil was superior to placebo in reducing IBS. One adverse effect of peppermint treatment was that patients more commonly reported heartburn than in the control group. (8)

However, a well-constructed randomized controlled trial from 2019 showed no difference in abdominal pain responses between peppermint oil and placebo. The authors concluded that peppermint oil did not meet the strict criteria for statistical significance. But as suggested by the authors, this negative result may be due to the small sample of 190 patients. (9)

Despite the strong evidence supporting peppermint oil as effective, it is unclear whether the benefits of persist long-term. One clinical trial showed that IBS symptoms returned two weeks after the trial ended. Therefore, peppermint oil may only be effective when consumed regularly. (10)

How does peppermint oil help in IBS?

The normal process of peristalsis – the contractions of smooth muscles of the gut – is altered in IBS. As such, sensations of pain, as well as bloating and other symptoms often arise. (10)

Peppermint oil contains antimicrobial, anti-inflammatory, and anesthetic properties that are thought to help relieve symptoms of IBS. An active ingredient in peppermint oil, menthol, is believed to reduce pain by acting on the smooth muscles of the gut. (11)

Menthol is a waxy compound that has a cooling effect and is found in a variety of health care products to treat pain. Menthol acts by blocking calcium channels and serotonin receptors in the muscles of the gut to relax smooth muscle and reduces symptoms of IBS. (12)

Capsule vs Tea

Peppermint oil for treating IBS is consumed in capsule form. The capsule contains an enteric coat that prevents the acid of the stomach from breaking it down. (13) This way, it can travel to the intestines without being dissolved. Peppermint in tea form has no proven benefit to help IBS, although it is unlikely to worsen symptoms. (14)

Peppermint oil capsules should be taken with water and not opened or chewed, as this may degrade the outer coat, and stop the outer coating from allowing the capsule to reach the bowel. The capsule may dissolve too early in the stomach rather than intestines. It is best to take the capsule at least 30 to 60 minutes before eating and not to consume the capsule too soon after a meal. (15)

Dosage

For most peppermint oil products, a person aged 15 years and above should take one capsule three times a day. If pain and discomfort is severe, this can be increased to a maximum of two capsules three times a day.

However, there is no standardized dosage of peppermint oil, and studies looking at peppermint oil have evaluated various dosages. It is therefore important to read the manufacturer’s label to take the appropriate dosage or consult with a medical professional before taking peppermint oil. (16)

Side effects

Peppermint oil is a safe and well-tolerated medicine. It generally causes fewer side effects than other types of antispasmodics. But as with any herb, peppermint oil may cause side effects in some people as this medicine can affect people in different ways. Since most studies of peppermint oil typically last less than eight weeks, the long-term safety of the medicine has not yet been evaluated.

Peppermint oil may cause symptoms such as:

• Heartburn or indigestion, especially if the capsule lacks an outer enteric coating

• Dermatitis if is applied to the skin

• Anal burning during diarrhea (17, 18, 19)

Although rare, peppermint oil may cause an allergic reaction in some people, and symptoms such as:

• Nausea

• Headache

• Mouth sores

• Flushing (20)

It is important to note that drinking alcohol may increase the risk of an allergic reaction that may cause a rash, loss of coordination, and shaking. If this happens, you should seek medical attention as soon as possible.

Peppermint oil and GERD

Peppermint oil relaxes the muscles between the esophagus and the stomach, the lower esophageal sphincter, and worsen symptoms in people with gastroesophageal reflux disease (GERD). GERD is a long-term condition in which acid from the stomach moves up into the esophagus. It is best to consult a doctor before taking peppermint oil if you are or have previously experienced GERD. (21)

Peppermint oil and other medications

Peppermint does not interact with most drugs. But you may wish to avoid taking peppermint oil at the same time as antacids – a type of indigestion medication. Antacids dissolve the outer coating of the peppermint oil capsule and may cause heartburn and nausea. You should take antacids at least two hours after peppermint oil capsules to avoid any interactions. (22)

Peppermint oil may also boost the blood level of some medications. These include the antidepressant amitriptyline (Elavil) and the statin simvastatin (Zocor). It is therefore best to consult your doctor to ensure it is safe for you to take peppermint oil. (23)

Should I take peppermint oil?

Not everyone with IBS finds that peppermint oil will improve symptoms. Some people may respond better to other types of antispasmodic medication. It is best to consult a doctor or pharmacist regarding alternative medicines if peppermint oil does not improve symptoms.  

Clinical benefits

Besides improving symptoms of IBS, peppermint oil has been used clinically to treat a variety of health conditions such as:

• Tension headache (24)

• Breastfeeding discomfort (25)

Non-oil alternatives

If you are suffering from IBS and concerned about the side effects of peppermint oil, there are several alternative treatment options. Since IBS is aggravated by stress and anxiety, lifestyle changes and psychological therapies may be of value such as:

• Gut-directed hypnotherapy: a form of guided entry into a state of deep relaxation with suggestions to alleviate bowel pain and discomfort. This form of therapy has been shown to be highly effective in several recent clinical studies. (26) An app like Nerva delivers gut-directed hypnotherapy to your phone, enabling you to use this technique from home.

• Cognitive-behavioral therapy (CBT): this form of therapy involves retraining the mind to perceive sensations of the gut as normal, and to respond to thoughts positively. CBT has been shown to help reduce the perception of pain in IBS. (27)

• Yoga: this ancient practice combines physical and mental practices to strengthen the mind-body connection. In one study, participants who practiced yoga three times per week reported less severe symptoms and reduced anxiety. (28)

• Low FODMAP diet: this well-balanced diet that is catered to addressing the specific symptoms of IBS. The diet removes common foods that trigger IBS symptoms and has been shown effective in several clinical studies. (29)

The Wrap Up

Peppermint oil is an essential oil that is useful for IBS. It produces fewer side effects than other antispasmodic medications and in capsule form, peppermint oil relieves abdominal pain by soothing the nerves of the gut and reducing inflammation. It is generally a safe and well-tolerated medicine. However, in rare cases, peppermint oil may cause heartburn or an allergic reaction.