MIAMI, Fla. -

From shampoo to sunscreen to shaving cream and a host of things in between, cosmetic products contain a variety of ingredients that can cause allergic reactions.

"It's an inflammation of the skin that may take hours, even days after you apply it and you have no clue what it could have been," explained Allergy Specialist Dr. Ileana Rodicio. "Even if it's the same make up you have used all your life, but there is a day that you get sensitized."

"Lately, I've been noticing I've been getting some itchy watery eyes and I've been thinking it's my mascara," said Shannon Krupp.

In an effort to pin down the culprit in her cosmetics, Krupp underwent an an advanced form of allergy screening offered by the Florida Center for Allergy and Asthma Care.

In one fell swoop, the cosmetic patch test can check for sensitivity to over 50 different cosmetic ingredients.

"It is important because once you know what ingredient you are allergic to you can look out and read labels and pick the cosmetic that is not containing that ingredient and then you have other choices," said Rodicio.

The process can take anywhere from two to four days to illicit an allergic response, during which time patients cannot wash their backs.  Reactions to the patch test can be mild, some itching and redness or severe, which could include blistering and burning.

"It's very easy in the sense of application but it can be uncomfortable," said Rodicio.

Turns out Krupp was allergic to Quaternium 15,  an ingredient commonly found in makeup and soap.  She's also allergic to formaldehyde, which is found in nail polish and glue for false eyelashes.