Summer 'margarita rash' after drinks and meals in the sun

— -- With temperatures rising many people are already dreaming about celebrating with a lime margarita or bloody Mary, while soaking up the sun.

While the lime in the margarita or celery in a bloody Mary may seem like the harmless ingredients, it turns out the seemingly innocent garnishes can actually be a health hazard. When they touch the skin, the area of contact may react with the sunlight and cause a skin condition called phytophotodermatitis.

What is phytophotodermatitis?

Phytophotodermatitis is a skin condition caused by plants that contain photo-sensitizing agents called psoralens, which make the area of the skin touched by the plant more sun sensitive. They are found especially in citrus fruits, including lemon and lime, as well as other fruits and vegetables like celery, parsley, figs and carrots.

Psoralens cause a sunburn-like reaction where they contact the skin that can develop into a red, itchy patch, according to the Mayo Clinic.

The skin may also have a blistering reaction if a higher concentration of the active ingredients are combined with a longer amount of time spent with UVA exposure. People in places closer to the equator have a higher risk for the skin reaction.

The condition is fairly common and the skin can become more sensitive within an hour of being exposed to the psoralen, according to Dr. Doris Day, a private practice dermatologist in New York and clinical associate professor at NYU Langone Medical Center.

"I see it every summer," Day told ABC News.

Margarita Rash

Most people get phytophotodermatitis after cooking, or infamously, after prepping limes for margaritas. Lime juice on the hands or arms can make the skin extra prone to a reaction even if the person is wearing sunblock.

Whenever a patient comes in to see Dr. Carolyn Jacob at her private dermatology practice in Chicago, presenting with phytophotodermatitis, she always asks about recent drinks.

"They say 'Doctor, I have this weird rash,' and I go 'How many limes did you have in your margarita in Mexico?'" Jacob said. "They gasp and say 'How did you know what I was doing?'"

People who like to cook outdoors also are at risk.

"I also warn cooks or bartenders who may deal with these ingredients prior to sun exposure," Day said. "This reaction is worse as the fruit or the vegetable gets older."

Beauty regimens may also be to blame

With many people interested in the trend toward more natural or botanical products including home-made facemasks, skin cleansers, fragrances, natural oils or even deodorants, experts say consumers should be careful that they don't slather themselves in products containing psoralen before heading into the sun.

"Everyone wants more natural products," Day said.

Some patients also use lemon to lighten their hair before laying in the sun, Day added. But, the lemon can trickle down the face and neck, causing problems upon exposure to the sun.

Day said many people don't realize that their food, beverage or skincare could have made their skin more sensitive to the sun and some are frightened by the reaction.

"People are always scared when they see something like this on the skin, especially if they have been naughty in the sun," Day said. "They come in and ask if they have skin cancer.”

How to recognize this rash

With phytophotodermatitis, what appears first usually looks like a burn or red rash, which can later become hyperpigmented, or brown, in the spots that the psoralen containing substance comes in contact with the skin. A splash of lime on the skin, can mean the hyperpigmentation in the shape of the splash later.

"I’ve seen patients where it’s still pink in one area and then it’s turning brown in one area" Jacob said. "We don’t understand why it leads to hyperpigmentation.”

How to keep skin safe

To prevent the rash patients should consider eating or using non-psoralen containing beverages, foods or beauty products while in the sun.

After indulging in a margarita or another psoralen-containing treat, hands should be washed thoroughly and immediately after contact. Broad-spectrum sunscreen or sunscreen specifically containing zinc oxide should be re-applied regularly.

UVA rays are the culprit in phytophotodermatitis -- and many common sunscreens do not filter them, according to Jacob.

Research has shown that zinc oxide has the best protection against UVA rays, she added. For children who may be consuming lemons or limes, there are kid-friendly sunscreen formulations containing zinc oxide available.

Physical protections like long-sleeved shirts or umbrellas can also minimize the risk.

Dr. Karen Kagha is a dermatology resident and a resident at ABC News Medical Unit