If you’ve ever bitten into a hot chilli pepper and felt that unmistakable burn spreading through your mouth, you’ve experienced capsaicin firsthand. This compound is responsible for the heat in peppers, and it’s been used medicinally for centuries across different cultures. Today, capsaicin is available as creams, patches, and oral supplements, sold in most countries without prescription for treating various types of pain.

But does capsaicin actually work? I’ve reviewed the clinical evidence, and the picture that emerges is interesting. For certain conditions, particularly nerve pain and arthritis, there’s solid research backing its use. For others, the evidence is thinner than the marketing would suggest.

What is capsaicin?

Capsaicin belongs to a family of compounds called capsaicinoids, which are found in chilli peppers. These alkaloids evolved as a defence mechanism. Plants produce them to deter animals from eating the fruit and to prevent fungal infections.

When you eat something spicy, capsaicin binds to pain receptors in your mouth, triggering that characteristic burning sensation. About 70% of the heat you feel from peppers comes specifically from capsaicin, with related compounds like dihydrocapsaicin contributing the rest 1.

Pure capsaicin was first isolated from peppers in 1876. It’s a colourless, odourless crystalline substance. By 1930, chemists had figured out how to synthesise it in the laboratory, which opened the door to pharmaceutical applications.

How capsaicin works in the body

Capsaicin acts through a specific receptor called TRPV1 (transient receptor potential vanilloid 1). This receptor normally responds to heat, acidity, and certain inflammatory chemicals. When capsaicin binds to TRPV1, it creates sensations of warmth, burning, or tingling.

Here’s where it gets interesting for pain treatment: repeated exposure to capsaicin causes the nerve endings to become desensitised. The receptors essentially become exhausted and stop responding normally. This is why capsaicin creams need to be applied consistently over days or weeks before they provide meaningful pain relief.

The NHS notes that capsaicin cream typically needs four applications daily for at least four weeks before patients can expect to see results 2. This isn’t a quick fix.

What the research shows: 7 potential benefits

1. Blood sugar control

Given capsaicin’s effects on metabolism, researchers have wondered whether it might help regulate blood sugar. People with type 2 diabetes often look for natural ways to support conventional treatments.

A systematic review examined 14 controlled trials looking at capsaicin’s effects on blood glucose and insulin levels 3. The conclusion was disappointing: no consistent benefits were found, whether for acute effects (right after taking it) or chronic effects (with ongoing supplementation).

What this means: If you’re hoping capsaicin will help with blood sugar, the research says probably not.

2. Cannabinoid hyperemesis syndrome (topical)

This is a niche but interesting application. Cannabinoid hyperemesis syndrome affects heavy cannabis users, causing cycles of severe nausea, vomiting, and abdominal pain. Sufferers often find temporary relief from hot baths or showers.

A systematic review of 7 trials involving 106 patients found that applying capsaicin cream to the abdomen helped reduce symptoms and shortened emergency department stays 4. The logic makes sense: capsaicin stimulates the same heat-sensing pathways that hot water does, providing similar relief without needing to stay in a shower for hours.

What this means: Applying capsaicin cream seems to help. The studies are small, but the logic is sound.

3. Weight loss and metabolism

The idea that spicy food can boost metabolism has been floating around for decades. Is there anything to it?

A meta-analysis of 9 studies found that capsaicin and related compounds (capsinoids) increased energy expenditure and fat oxidation in people with a BMI over 25 5. The main mechanism seems to be thermogenesis - your body generates more heat, burning extra calories in the process.

The practical effects are modest though. We’re talking marginal increases in calorie burning, not dramatic weight loss. Capsaicin might give a small boost to other weight management efforts, but eating chillies won’t undo a poor diet.

What this means: Don’t expect miracles. It’s a minor metabolic nudge at best.

4. Cardiovascular risk factors

Heart disease remains the leading cause of death globally, so anything that might reduce risk factors attracts interest. A randomised controlled trial followed 42 patients with dyslipidemia (abnormal blood fats) for three months 6.

Participants taking capsaicin capsules showed increased HDL cholesterol (the “good” cholesterol) and reductions in triglycerides and C-reactive protein (an inflammation marker). These are meaningful changes, though the study was small.

Similar to the effects of fish oil and other supplements affecting lipid profiles, capsaicin appears to work through multiple pathways involving metabolism and inflammation.

What this means: The early data looks promising for cholesterol, but with only 42 participants, I wouldn’t bet the farm on it.

5. Athletic performance

Sports supplements are a massive market, and researchers have tested capsaicin’s effects on exercise performance. A small randomised trial with 10 active men found that capsaicin supplementation reduced running time and perceived exertion during a mid-distance test 7.

Blood lactate levels were unchanged, suggesting the improvement wasn’t from better energy metabolism per se. The effect might work through pain perception or motivation rather than physical capacity.

What this means: Maybe helpful for running, but 10 participants is barely a study. More research needed.

6. Osteoarthritis pain (topical)

This is one of capsaicin’s better-supported applications. Osteoarthritis causes joint pain and stiffness, affecting millions of people worldwide. Current treatments focus mainly on pain management since nothing has been proven to reverse cartilage damage.

A large meta-analysis examined 28 randomised controlled trials involving over 7,000 people with osteoarthritis 8. Both topical capsaicin and topical NSAIDs (like diclofenac gel) outperformed placebo for pain relief. The two treatments weren’t directly compared in head-to-head trials, but their effect sizes appeared similar.

Capsaicin works here by depleting substance P, a neurotransmitter involved in pain signalling. With regular application, the nerves in the affected area become less sensitive.

What this means: This is where capsaicin actually shines. Solid evidence, over 7,000 participants. Worth trying if NSAIDs upset your stomach.

7. Diabetic peripheral neuropathy (topical)

Nerve damage from diabetes causes burning or stabbing pain in the feet and hands. It’s notoriously difficult to treat. Many oral medications help with the pain but leave patients feeling drowsy and foggy all day.

A meta-analysis of 25 randomised controlled trials compared high-strength capsaicin patches (8%) to oral medications 9. The patch provided comparable pain relief but with far fewer systemic side effects. People on oral drugs were more likely to feel tired during the day and more likely to stop treatment altogether.

This makes capsaicin patches an attractive option for people with diabetic bladder dysfunction and related complications who are already dealing with multiple medications.

What this means: The 8% patches work as well as pills but don’t make you drowsy. That’s a real advantage.

Side effects of capsaicin

Oral capsaicin at normal doses is generally safe for adults in the short term. That said, your stomach may disagree. Common complaints include:

Heartburn and acid reflux
Sweating (your body thinks it’s hot)
Nausea or loose stools
Runny nose

Topical application commonly causes a local burning sensation, especially during the first few applications. This usually diminishes with continued use as the nerves become desensitised.

Rarely, very large doses or prolonged use might stress the liver or kidneys, though this is uncommon with normal supplementation.

Safety precautions: 8 contraindications

Pregnancy, breastfeeding, and children: Don’t use capsaicin (orally or topically) if you’re pregnant, nursing, or giving it to a child. Safety data for these groups is lacking.
Open wounds or broken skin: Never apply capsaicin cream to damaged skin. It will cause intense burning, redness, and irritation.
Respiratory sensitivity: Inhaling capsaicin can trigger coughing, sneezing, and breathing difficulties. Be careful when handling powdered forms.
Before surgery: Stop taking capsaicin at least two weeks before any scheduled surgery due to potential anticoagulant effects.
Anticoagulant medications: Capsaicin may enhance bleeding risk when combined with blood thinners including aspirin, warfarin, heparin, clopidogrel, enoxaparin, and NSAIDs like ibuprofen and naproxen.
Theophylline: This bronchodilator medication may interact with capsaicin, potentially affecting drug levels or increasing side effects.
ACE inhibitors: Some blood pressure medications (captopril, enalapril, lisinopril, ramipril) can cause cough as a side effect. There’s a case report of capsaicin worsening this cough, though whether this interaction is clinically significant remains unclear.
Chilli allergy: If you’ve had allergic reactions to peppers, avoid capsaicin in any form. Symptoms of an allergic reaction include throat tightening, difficulty breathing or swallowing, facial swelling, and skin rash.

Practical recommendations

If you’re considering capsaicin for pain relief, the topical forms have the strongest evidence behind them. For conditions involving nerve pain or joint discomfort, creams containing 0.025% to 0.1% capsaicin are widely available. Higher-strength patches (8%) are typically used under medical supervision for more severe neuropathic pain.

Apply creams four times daily for at least four weeks before judging effectiveness. The initial burning sensation is normal and usually decreases with continued use. Wash hands thoroughly after application, and avoid touching eyes, nose, or mouth.

For oral supplements aimed at metabolism or cardiovascular effects, the evidence is less convincing. If you want to try them anyway, start with a low dose to see how your stomach handles it.

One important note: if you’re taking blood thinners or blood pressure medication, talk to your doctor first. The interactions listed above aren’t theoretical - they can cause real problems.

References

Rollyson WD, et al. Bioavailability of capsaicin and its implications for drug delivery. J Control Release. 2014;196:96-105.
NHS. Capsaicin cream. 2024. Available at: https://www.nhs.uk/medicines/capsaicin-cream/
Sanati S, et al. The effects of capsaicin supplementation on glucose and insulin: A systematic review and meta-analysis of controlled trials. Crit Rev Food Sci Nutr. 2022;62(5):1327-1338.
Richards JR, et al. Treatment of cannabinoid hyperemesis syndrome with capsaicin: A systematic review. Pharmacotherapy. 2021;41(5):433-442.
Zheng J, et al. Dietary capsaicin and its anti-obesity potency: from mechanism to clinical implications. Biosci Rep. 2017;37(3):BSR20170286.
Sanati S, et al. A randomized controlled trial on the effect of capsaicin on inflammation and lipid profile in dyslipidemic patients. Avicenna J Phytomed. 2017;7(5):417-424.
de Freitas MC, et al. Acute capsaicin supplementation improves resistance training performance. J Strength Cond Res. 2018;32(8):2227-2232.
Rafanan BS Jr, et al. Efficacy of topical agents for osteoarthritis: A systematic review and network meta-analysis. J Orthop Traumatol Rehabil. 2018;10(2):60-65.
van Nooten F, et al. Capsaicin 8% patch versus oral neuropathic pain medications for the treatment of painful diabetic peripheral neuropathy: A systematic review and meta-analysis. Diabetes Ther. 2017;8(3):485-499.