Biofreeze does not have any common side effects, but serious side effects can include severe irritation and allergic reactions, according to Drugs.com. Allergy symptoms can include itching, difficulty breathing, rash, hives, chest tightness, and swelling in the face, mouth, tongue and lips.
Biofreeze is a topical pain reliever made from camphor and menthol. It is meant to provide muscle and joint pain relief through the menthol's cooling action. It should not be applied internally, on broken skin or on irritated skin. If the pain is still present after seven days or it stops and restarts, Drugs.com recommends contacting a doctor.