Activated charcoal tablets: uses and risks

What do activated charcoal tablets do?

Activated charcoal tablets bind other substances to the charcoal's surface while it passes through your gut, so less of them gets into your body. As a food supplement in Great Britain, activated charcoal has a single authorised health claim: activated charcoal contributes to reducing excessive flatulence after eating. The claim only applies to a product with 1 g of activated charcoal per portion, and the label must tell you the effect is obtained with 1 g taken at least 30 minutes before the meal and 1 g shortly after it.

Hospitals use activated charcoal too, as a drink for some types of poisoning. That's a medical treatment, at far higher doses, and nothing you should attempt at home.

How does activated charcoal work?

It works by adsorption: molecules stick to the surface of the charcoal rather than soaking into it. A 2016 review in the British Journal of Clinical Pharmacology explains that medicinal charcoal is made by heating carbon-based materials such as coconut shells or peat, then "activating" it with gases at high temperature. This leaves an extremely porous material: some preparations have a surface area of up to 3,500 square metres per gram, and a large football pitch is about 10,000 square metres.

Drugs and other compounds cling to that surface through weak chemical forces. Organic compounds bind more readily than dissociated inorganic ones, and some things hardly bind at all, including metals such as iron and lithium. The charcoal carries what it has bound out of the body in your poo, which is why it turns poo black.

How to take activated charcoal for gas and bloating

For wind, follow the conditions of the authorised claim: 1 g at least 30 minutes before the meal and 1 g shortly after. There's no authorised claim for bloating. A claim that activated charcoal contributes to digestive comfort, assessed for reducing bloating, was not authorised in Great Britain, so a product can't be sold for it.

The research behind charcoal and wind is small and old, and it points both ways:

• A 1981 study found that charcoal prevented the usual rise in wind and breath hydrogen after a gas-producing meal.
• A 1985 double-blind study found no difference in breath hydrogen or wind after a baked bean meal with 4 g of charcoal.
• A 1986 trial of 99 people in the US and India found lower breath hydrogen and fewer symptoms of bloating and cramps on charcoal after a sugar that ferments in the gut.
• A 1999 study of five volunteers taking 0.52 g four times a day for a week found no fall in the sulphur gases that make wind smell.

The NHS suggests simpler steps first. Eat smaller meals more often, eat slowly with your mouth closed, and cut down on foods that cause wind, such as beans, cabbage, broccoli, onions and dried fruit, along with fizzy drinks, alcohol, chewing gum and smoking. Regular exercise and peppermint tea may help. A pharmacist can suggest a medicine such as simeticone. If you've recently added fibre, wind is a common early side effect; our guide to psyllium husk covers building up slowly.

See a GP if wind is affecting your life and self-help and pharmacy treatments haven't worked, or if you have a stomach ache or bloating that won't go away or keeps coming back, repeated constipation or diarrhoea, weight loss without trying, or blood in your poo.

Charcoal tablets, capsules, pills or powder: which format?

Charcoal tablets, capsules and pills (a common name for either) are the same material, so the dose matters more than the format. The authorised claim needs 1 g per portion, which can mean several capsules or tablets, so check how many milligrams of activated charcoal each one contains and how many make up a serving. Powder is messy, stains and is hard to measure accurately, so capsules or tablets make a 1 g dose easier. A sensible label states the amount per serving, gives directions that match the claim's conditions and tells you to keep it apart from medicines.

Can you buy activated charcoal in the UK?

Yes. In Great Britain activated charcoal is sold as a food supplement. The Food Standards Agency (FSA) says food supplements are regulated as food, not medicine, so they can't be sold with claims that they prevent, treat or cure a medical condition. The only authorised health claim for charcoal is the one for excessive wind after eating, and it comes with the conditions described above.

The FSA's advice for buying any supplement applies here. Check that any health claim appears on the Great Britain register, read the label's dose and warnings, and don't go over the recommended dose. Be careful with online marketplaces, where the seller and the product's origin may be unclear, and wary of counterfeits sold at a price far below everyone else's. Whatever you buy, keep the two-hour gap from medicines described below, and ask a pharmacist before starting if you take regular prescriptions.

Side effects and medicine spacing

Most of activated charcoal's side effects are digestive.

• It turns your poo black, which is expected.
• It can cause constipation, stomach discomfort and vomiting, according to the Singapore Ministry of Health's HealthHub medicine guide.
• Bowel blockages have been reported after charcoal, mostly at poisoning doses. People with a slow-moving gut, or who take opioid painkillers or anticholinergic medicines, may be at higher risk, so check with a pharmacist first if that applies to you.
• Stop taking it and see a doctor if you get severe stomach pain, blood in your poo or a fever, as HealthHub advises.

Because charcoal stops many medicines getting into the body, patient guidance from HealthHub and a Lexidrug leaflet published by Memorial Sloan Kettering Cancer Center advises leaving a two-hour gap between charcoal and other medicines. That applies to anything you take by mouth, including the contraceptive pill, and it's sensible to keep other supplements apart from it as well. Our guide to taking supplements together covers other timing questions.

Does activated charcoal whiten teeth or "detox" your body?

The evidence doesn't support either use. A 2017 review in the Journal of the American Dental Association found insufficient clinical and laboratory data to back the safety and whitening claims of charcoal toothpastes and powders, and some of the studies it found reported enamel wear or more tooth decay. A 2023 systematic review of laboratory studies concluded that charcoal toothpastes whiten less than other options and are more abrasive. HealthHub also notes that charcoal taken as a medicine can temporarily discolour teeth.

"Detox" products make similar promises without the evidence. A 2015 review of detox diets in the Journal of Human Nutrition and Dietetics found very little clinical evidence for them and no randomised controlled trials of commercial detox diets in people. Taking charcoal routinely to "clean out" your system also risks binding the medicines you do want absorbed.

Where Natura fits

Daily Charcoal, in the Natura cabinet (coming soon), gives 1,000 mg of activated charcoal per three capsules, taken as three capsules (1 g) at least 30 minutes before a meal and three capsules (1 g) shortly after. Activated charcoal contributes to reducing excessive flatulence after eating. It will be sold as a single bottle, and the two-hour medicine gap above applies to it.