Over-the-counter superglue contains ethylcyanoacrylates, which break down in the body to toxic byproducts.
Medical superglues contain a slightly different chemical: octylcyanoacrylates, which don't break down into toxic substances.
In technical terms: "Upon application to living tissues (water or base), the monomer undergoes an exothermic hydroxylation reaction that results in polymerization of the adhesive. The shorter-chain derivatives [ie, the over-the-counter stuff] tend to have a higher degree of tissue toxicity than the longer-chain derivatives [ie, the FDA approved medical glues] do.
Inflammation, tissue necrosis, granulation formation, and wound breakdown can occur when cyanoacrylates are implanted subcutaneously. The process causing the histologic toxicity is thought to be related to the by-products of degradation, cyanoacetate, and formaldehyde. The local concentrations of these breakdown products are proportional to the rate of degradation (an aqueous degradation process) of the parent compound. Therefore, slower degradation rates result in less toxicity to the tissues."
From eMedicine Specialties > Otolaryngology and Facial Plastic Surgery > Pharmacology
Wound Adhesives, 2-Octyl Cyanoacrylate
Author: Nathan D Schwade, PhD,http://emedicine.medscape.com/article/874047-overview
Updated: Sep 17, 2008