Is it normal to experience extreme eye swelling after a Cosmelan treatment?

Treating PIH and melasma with cosmelan may make your skin hypersensitive. I would suggest Melarase creams and Elevase Moisture Booster as part of the post-treatment regimen to reduce redness and pigmentation risk.
Best, 
Dr. Karamanoukian
Realself100 Surgeon

Some swelling after Cosmelan treatment is acceptable, but if the swelling is severe allergic reaction must be considered.

It is normal for some patients to experience swelling after the cosmelan treatment & around the eye area. It usually is not from an allergic reaction.

NO there should be no swelling if used as directed.
You probably are having an allergic reactio to one of the ingredients. See your internist to treat the allergic reaction.

In addition to a variety of acids, Cosmelan also contains botanicals that can incite allergic reactions. To answer your question, it is NOT normal for you to be experiencing what appears to be an allergic reaction. I would seek the care of your doctor as soon as you are able to do so. If you are coughing or experiencing difficulty breathing, you should go to the emergency room immediately.