Aloe vera topical gel is generally well-tolerated, but there have been reports of hypersensitive skin reactions.[1]
Additionally, Aloe vera latex, a yellow-brownish liquid extracted from the skin of the plant's leaves and traditionally used as a laxative, and Aloe vera whole leaf extract, which contains the latex, may pose a risk of toxicity due to the latex’s high content of anthranoids.[2][3]
Topical and oral use of Aloe vera can also theoretically cause skin irritation, urticaria, cramping, and diarrhea in people who are allergic to other plants in the same family (e.g., onion).[2]
Regarding interactions with medications, there is evidence of a potential herb-drug interaction between Aloe vera whole leaf extract and sevoflurane, a general anesthetic.[2]
Finally, Aloe vera has been associated with cases of acute hepatitis (liver inflammation). This side effect typically occurs within an oral dosage range of 250–500 mg per day, and while the effects appear reversible, the exact mechanism of toxicity is not fully understood.[4][5][2]