I most regularly use charcoal to brush my teeth as it whitens them naturally. I keep it on hand in case any of the kids ever ingest any toxins or household chemicals, though we also do our best to keep anything toxic out of the house completely. In case of any emergency, I would absolutely call a poison control center (we keep the number with all emergency numbers on our fridge) and follow their directions, but this basic use guide is also helpful.
I have personally used charcoal to treat a spider bite on my son’s leg (we had confirmation that it was likely a brown recluse bite and a mix of charcoal and baking soda helped draw the toxin out and he healed with no long term scarring. I’ve also used it when I got food poisoning (another good reason not to eat out!) and was able to get rid of it within a few hours with charcoal followed by apple cider vinegar and then epsom salt (to avoid the charcoal building up in my system).
As with any substance, you should always check with a doctor or medical professional before use, especially in an emergency or life threatening situation or if there is any other underlying health problem.
Activated charcoal is not known to be toxic, though it should not be taken within two hours of vitamins or medications because it will keep the body from adsorbing them. Care should also be taken to find a high quality form of charcoal. I personally would not take charcoal on a regular basis and would only use as needed. This article has a full list of precautions.
Also, activated charcoal is NOT the same thing as the ashes from burning wood or other fires at home, so please don’t try to use those type of ashes for these or any other uses!
“That’s how powerful activated charcoal is as an emergency decontaminant in the gastrointestinal (GI) tract, which includes the stomach and intestines. Activated charcoal is considered to be the most effective single agent available. It is used after a person swallows or adsorbs almost any toxic drug or chemical”