Activated charcoal can act as an adsorbent (kind of a "chemical sponge") to bind toxins in the gut. If you use a preparation that is safe for people and use a smaller dose, it should be harmless.
If the problem was an insect sting, I doubt that there are any toxins in the gut that the charcoal would help with.
So many times we are unable to determine the source of the allergen.
Kenalog is a long-acting corticosteroid (cortisone) injection that stays in the body for weeks, where the dexamethasone lasts only a couple of days.
Antihistamines like benadryl are often helpful for something like an insect sting, even though most dogs don't get much relief from them in regard to allergic itching.
Prior to coming to Weill Cornell Medical College, Ms. Geller was a clinical specialist at the Cochlear Implant Center at New York University Hospital and Director of the Shelley and Steven Einhorn Communication Center at the Center for Hearing and Communication. She is responsible for the development and implementation of the cochlear implant aural rehabilitation program, the supervision of the day-to-day activities for speech pathology, as well as for direct service provision for pediatrics and adults with hearing loss and cochlear implants. Her clinical expertise is in the assessment and treatment of individuals with hearing loss and cochlear implants. X Chandler Thompson, DMA, MS, CCC-SLP Speech Language Pathologist