Latisse and Benzalkonium Chloride

Can one be allergic?

Irritation happens from time to time in users of Latisse. It's not all that common but redness of the eyelid and even the eye can occur. Rarely a patient develops itching or rashes on the skin and asks "Could this be related?"

This is a complex question. Latisse contains bimatoprost as well as the preservative benzaalkonium chloride (BAC) at a concentration of 0.05 mg/mL. This preservative has been around since 1935. It is quite common in many products, especially those used around the eye. BAC is more likely to cause irritation than true allergy but certainly cases of allergic reactions can occur with BAC even serious ones. Studies at the Mayo clinic published in 2016 (see reference below) suggested that allergies to BAC might be increasing in the population. In fact, the allergen climbed up the list to now be one of their top 10 allergens they see in their clinic.

If a patient has a skin rash, it is far more likely that an allergy exists if the eyelids show some redness. If the eyelids look perfectly fine, it is much less common that the cause if the skin rash is related to Latisse use. But even without redness a systemic allergic response is still "possible". It's just much less likely. With these sorts of situations, I like to know the whole story (and see the rashes if they are present). I like to know if the patient uses products containing BAC in the past and if so, what types of reactions they had. It's a good idea to review the whole story with your physician. If it was only itching, one might (on the advice of the doctor) wait for the itching to go away completely and either try again or have a specialized physician test the product's allergic potential on the skin as a prick or patch test. However, if there was any runny nose, cough, chest tightness, wheezing, shortness of breath, dizziness, throat tightness, swollen tongue or eyelid should should seek the advice of an allergist physician.

Overall, irritation from Latisse is much much more common than allergy. Nevertheless, if one is experiencing new or unusual type skin, mucosal or respiratory issues one must consider whether a true allergic response could be responsible


Wentworth, A et al. Benzalkonium Chloride: A Known Irritant and Novel Allergen. Dermatitis 2016.


Dr. Jeff Donovan is a Canadian and US board certified dermatologist specializing exclusively in hair loss. To schedule a consultation, please call the Whistler office at 604.283.1887

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