The U.S. Food and Drug Administration issued a Public Health Advisory to alert consumers, patients, health care professionals, and caregivers about potentially serious and life-threatening side effects from the improper use of skin numbing products. The products, also known as topical anesthetics, are available in over-the-counter (OTC) and prescription forms.
The FDA strongly advises consumers not to:
- make heavy application of topical anesthetic products over large areas of skin;
- use formulations that are stronger or more concentrated than necessary;
- apply these products to irritated or broken skin;
- wrap the treated skin with plastic wrap or other dressings; and
- apply heat from a heating pad to skin treated with these products.
I have discussed these potentially dangerous side effects here:
Risks in hair removal pain management
Topicals over large areas: should be avoided
Risks:
impairs ability to gauge overtreatment
dangerous in combination with pain medications
can cause severe allergic reaction
use on a large area can reach toxic levels of drug absorption
Topical preparations are generally a very good option to reduce hair removal pain, but it’s important to be careful when using them on large areas like the back or legs. Do a test with the product on a small area, then wait a few days before undergoing a procedure using a large dose. If you have a noticeable skin reaction to the test dose (itching, blistering, skin color change lasting more than a few hours), you should not use the topical over a large area.
Full article: (fda.gov)