Pneumonitis and bronchiolitis obliterans have been reported after pulmonary aspiration of gastric contents containing activated charcoal.
Constipation (may be prevented by co-administration of a cathartic, although this is not routinely advised).
Diarrhea, dehydration, hypermagnesemia, and hypernatremia resulting from co-administered cathartics, especially with repeated doses of charcoal and cathartics or even after a single large dose of a premixed sorbitol-containing charcoal product.
Intestinal bezoar with obstruction (in particular with multiple doses given to patients who have impaired bowel motility).
Corneal abrasions have occurred when activated charcoal was spilled in the eyes.
Use in pregnancy. Activated charcoal is not systemically absorbed. Diarrhea resulting in shock or hypernatremia in the mother could conceivably affect the fetus adversely.