Can you take too much activated charcoal?
July 17, 2014 12:47 AM   Subscribe

Activated charcoal is often given for various poisonings, but can you overdose on it? What would happen if you took it every day?
posted by devnull to Health & Fitness (6 answers total) 1 user marked this as a favorite
You'd poo black and get constipated.
posted by sukeban at 1:04 AM on July 17, 2014 [2 favorites]

Would it affect the absorption of other nutrients that the body needs?
posted by devnull at 1:24 AM on July 17, 2014

"activated charcoal is safe for most adults when used short-term. Side effects of activated charcoal include constipation and black stools. More serious, but rare, side effects are a slowing or blockage of the intestinal tract, regurgitation into the lungs, and dehydration."

"Activated charcoal absorbs substances in the stomach and intestines. Taking activated charcoal along with medications taken by mouth can decrease how much medicine your body absorbs, and decrease the effectiveness of your medication. To prevent this interaction, take activated charcoal at least one hour after medications you take by mouth."

IANAScientist/doctor, but it seems to me that if activated charcoal decreases the absorption of medications, it would also decrease the absorption of nutrients.
posted by cooker girl at 6:23 AM on July 17, 2014

I'm on a phone so can't cite, but I have heard malabsorption of nutrients is a side effect of too much, which isn't surprising.
posted by blue suede stockings at 6:59 AM on July 17, 2014

This drug monograph for activated charcoal recommends against "routine use of single-dose activated charcoal for the management of poisoning", and highlights the side-effects cooker girl has noted above.

Logically the mechanism by which it mitigates poisoning, interfering with absorption of toxic substances, could also disrupt absorption of nutrients.
posted by onshi at 7:21 AM on July 17, 2014

Would it affect the absorption of other nutrients that the body needs?

Likely, yes. Activated charcoal works specifically by providing a large number of binding sites for other substances so that they don't get absorbed into your body. Essentially, it's like a large sticky surface area that a lot of stuff can get stuck on. But not everything and anything can get stuck on activated charcoal, and once the whole sticky surface is full, it can't stick to anything else. So it will depend on your daily dose of AC and your daily dose of whatever the substance in question is.

Activated charcoal binds best to organic substances. Examples: it binds very well to iodine. You need iodine to avoid developing hypothyroidism, and we don't typically eat huge amounts of it in our diet. Therefore, I theorize that a person taking daily AC would develop iodine deficiency. It also binds well to poorly water-soluble and large molecules like fatty acids. However, we have a lot of fatty acids in our diets.

AC has mostly been studied for its effects on human poisons, rather than on nutrients (although some nutrients are also poisons, depending on the dose - like potassium, which is very dangerous if levels in our body get too high. Studies have shown that potassium doesn't bind well to AC). Therefore, it will be hard to find much data on which nutrients, aside from those that are also common toxins, stick or don't stick well to AC, although one can guess from the chemical properties based on the generalities noted above.

Side note: AC is often combined with sorbitol (a sugar alcohol) which makes the taste more tolerable and acts as a cathartic laxative to combat the constipating effects of AC. If the person who takes the charcoal is awake and alert, they are unlikely to risk aspiration of the AC into the lungs - that typically happens because poisoning victims treated with it are sleepy and don't have a normal gag reflex, and start vomiting mid-treatment.
Second side note: wow, doing a little reading on this question is a good way to realize how much misinformation there is on the inter web about using AC as a general health tonic!
posted by treehorn+bunny at 5:50 PM on July 17, 2014 [1 favorite]

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