The Truth About Activated Charcoal
You may have seen a post going around warning people to avoid foods colored with activated charcoal because it can interfere with certain medications. This is well-meaning advice, but the facts about what activated charcoal actually does have been muddled. FIRST: Activated charcoal only affects the gastrointestinal tract. That means:
If you take long-acting birth control via injection, or have a birth control implant, activated charcoal will not interfere with that medication. AC can only interfere with birth control that is taken orally, i.e., the pill.
If you take hormones via injection, or by applying it to your skin (as a gel, dermal patch, et cetera), activated charcoal will not interfere with that medication.
If you take insulin via injection or a subcutaneous pump, activated charcoal will not interfere with that medication.
Activated charcoal works exclusively within the gastrointestinal tract. It adsorbs (different from absorbs) chemicals that are dissolved into liquid form and which the AC makes direct, physical contact with. It cannot affect anything that doesn't go through the gastrointestinal tract! Medications (or drugs, or poisons) that you take as injections, inhalants, vaginal suppositories, and/or topical treatments cannot be affected by activated charcoal.
SECOND: Even if you take your medication orally (or through a tube that enters the stomach or intestines, or as a rectal suppository) it may not be chemically able to be adsorbed by AC. Activated charcoal does not significantly affect:
Metals (incl. lithium; iron, calcium, or zinc supplements)
Electrolytes (incl. magnesium, sodium, or potassium supplements)
Alcohol
Furthermore, AC loses effectiveness if taken more than one hour after a substance is ingested, and even with very high doses or delayed-release drugs, four hours is the limit for it to be considered to have any clinical effect at all. If you take medication (or drugs) more than four hours prior to ingesting AC, the vast majority of the chemical will have already been absorbed through the stomach/intestinal lining and into the bloodstream before the AC has a chance to reach it.
Also, this is considering activated charcoal at maximum pharmacological efficacy -- at the strength it is used in emergency rooms. Charcoal purchased at craft or food supply stores, or online, may not be nearly as potent as the medical-grade stuff hospitals use to treat poisoning. It may not be "activated" at all! Activated charcoal is made through a special process of heating charcoal in high-temperature, low-oxygen environments and then mixing it with other chemicals to eliminate any remaining contaminants. It's very likely that the "activated charcoal" on store shelves is just normal charcoal, aka "burnt plant material."
There are other reasons not to use AC as a food additive (constipation, teeth staining, dehydration) but it will not magically render all your medications null and void, and it certainly won't "flush out" hormone replacement therapy -- even if it inhibits your body's absorption of oral HRT medications like estradiol, it absolutely will not affect any hormones that have already entered your bloodstream. Consider that people have never worried about AC interfering with natively-produced hormones. There is no mechanism by which activated charcoal, or any substance, can differentiate between which hormones your body made on its own and which ones were taken as HRT. Again: activated charcoal does not have any effect on hormone levels in the blood. It is entirely limited to the gastrointestinal tract.
Please try and take a moment to fact-check any post you see that makes any claim about medication interactions, contraindications, overdoses, or side effects. Even if the post seems to be offering well-meaning "better safe than sorry" advice, this is a serious, delicate subject, and misinformation about medicine can have disastrous consequences (I'm looking at you, horse dewormer)
The main source of this information is this article from StatPearls. Information about potential side effects of activated charcoal consumption comes from this article by INTEGRIS.
