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Chilli and cayenne (capsaicin)
Chilli and cayenne (capsaicin) — what the European monograph actually supports, what it is not for, the form and how long it is meant to be used, side effects, and the 2 medicine interactions documented for it.
This is a reference page, not a diagnosis and not a prescription. Herbal products are real pharmacology: they have effects, side effects and interactions with medicines. Tell your doctor and your pharmacist everything you take, including teas and supplements, and never stop or change a prescribed medicine because of anything you read here.
What it is
Capsicum annuum L. and related species — fruit (Capsici fructus)
Local names across the region this site serves: tšillipipar (ET) · chili (FI) · кайенский перец (RU).
Grouped here under Kitchen spices with a safety story. Regulatory position: Food and spice; capsaicin itself is a licensed prescription and pharmacy medicine in specific topical strengths.
What the evidence supports
The registered indication: Topical relief of muscle and joint pain in low-strength preparations; high-concentration capsaicin patches are licensed medicines for peripheral neuropathic pain.
Capsaicin, the compound that makes chilli hot, binds TRPV1 — a receptor on sensory nerve endings that normally reports heat. That is why chilli feels hot rather than tasting hot, and why cold water does not help while fat and dairy do. Applied repeatedly to skin, capsaicin first excites and then defunctionalises those nerve endings, and that is a genuine analgesic mechanism rather than a folk one: high-concentration capsaicin patches are licensed prescription medicines applied in a clinic for peripheral neuropathic pain, and low-strength creams and plasters are sold for muscle and joint pain. This is a case where the pharmacy product and the kitchen spice really do share a mechanism, and where the pharmacy product is measured and the kitchen one is not.
B — Traditional use, trials point the same way Registered on long-standing use, and independent reviews of human trials point in the same direction without settling the question.
What it is not for
Eating chilli as a treatment for anything. There is no good evidence that chilli causes stomach ulcers, and none that it cures them.
Form, strength and how long
Fresh and dried fruit, cayenne powder, oleoresin, and topical creams, plasters and patches of defined capsaicin strength.
Duration. Topical products are used in courses; the burning sensation usually diminishes over several days of consistent use, which is part of how they work.
No gram figure appears on this page on purpose. The plant part, the extraction solvent and the drug-to-extract ratio together define a preparation, and a number taken from one does not describe another. The reasoning is set out on the hub; the amount that applies to you is the one printed on the pack you are holding, and a pharmacist will read it with you.
Side effects
Burning at the application site is expected and can be severe. Never apply to broken skin, near the eyes, or on mucous membranes, and wash hands thoroughly afterwards — capsaicin transferred to an eye is memorable for the wrong reasons. Heat from a shower, sun or exercise intensifies the burning. Eaten, it causes mouth and gut discomfort in some people and worsens reflux.
Who should avoid it
Keep topical products away from children. Do not use a heat pad or hot bath over a capsaicin application.
Interactions with medicines
| Medicine or substance | What is described |
|---|---|
| Blood-pressure medicines, diuretics and corticosteroids | Cough associated with ACE inhibitors has been reported to worsen with topical capsaicin, which shares a sensory-nerve mechanism with that side effect. |
| Prescription medicines generally | Do not combine a capsaicin product with a heating pad or hot compress; the combination has caused burns. |
The reverse view — start from the medicine rather than the plant — is in the medicine, food and alcohol interactions reference, and summarised for every herb on this site.
As a food
This one is also in the kitchen, so the nutrition figures are worth having next to the pharmacology: see the food data page for calories and nutrients per 100 g and per portion. Culinary amounts and medicinal preparations are different exposures, and the difference is usually the whole safety story.
Sources: NIH National Center for Complementary and Integrative Health — herb fact sheets · checked 2026-09-06
Frequently asked questions
What is chilli and cayenne (capsaicin) used for?
Topical relief of muscle and joint pain in low-strength preparations; high-concentration capsaicin patches are licensed medicines for peripheral neuropathic pain. Capsaicin, the compound that makes chilli hot, binds TRPV1 — a receptor on sensory nerve endings that normally reports heat. That is why chilli feels hot rather than tasting hot, and why cold water does not help while fat and dairy do. Applied repeatedly to skin, capsaicin first excites and then defunctionalises those nerve endings, and that is a genuine analgesic mechanism rather than a folk one: high-concentration capsaicin patches are licensed prescription medicines applied in a clinic for peripheral neuropathic pain, and low-strength creams and plasters are sold for muscle and joint pain. This is a case where the pharmacy product and the kitchen spice really do share a mechanism, and where the pharmacy product is measured and the kitchen one is not.
Does chilli and cayenne (capsaicin) work?
Graded B here: Registered on long-standing use, and independent reviews of human trials point in the same direction without settling the question. Eating chilli as a treatment for anything. There is no good evidence that chilli causes stomach ulcers, and none that it cures them.
How much chilli and cayenne (capsaicin) should I take?
This reference does not print gram figures, because they do not transfer between preparations of different extract strength. What can be said honestly is the form and the duration: Fresh and dried fruit, cayenne powder, oleoresin, and topical creams, plasters and patches of defined capsaicin strength. Topical products are used in courses; the burning sensation usually diminishes over several days of consistent use, which is part of how they work.
What are the side effects of chilli and cayenne (capsaicin)?
Burning at the application site is expected and can be severe. Never apply to broken skin, near the eyes, or on mucous membranes, and wash hands thoroughly afterwards — capsaicin transferred to an eye is memorable for the wrong reasons. Heat from a shower, sun or exercise intensifies the burning. Eaten, it causes mouth and gut discomfort in some people and worsens reflux.
Does chilli and cayenne (capsaicin) interact with medicines?
Yes — documented for Blood pressure, Prescriptions. Each one is described on this page, with a link to the medicine-side reference where one exists.
Others in kitchen spices with a safety story
Cinnamon
Nothing that survives a systematic review. It is a spice with a real safety figure attached.
Garlic
Relief of symptoms of mild circulatory complaints, in traditional-use preparations. Not the treatment of cardiovascular disease.
Nutmeg
Nothing medicinal. It is on this list because it is the kitchen spice that poisons people.
Green tea extract
Marketed for weight loss and metabolism. Neither claim survives review.
Keep the whole list in one place
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