During your next picnic or backyard BBQ, you might want to be wary of making lemonade or squeezing a lime into a drink outside. Getting fruit juice on your skin while the sun is beaming can result in a really nasty chemical burn. How, you ask? Phytophotodermatitis is a skin condition caused by the chemicals in some fruits and plants – namely limes, lemons, and celery that make your skin hypersensitive to sun and can often trigger a reaction. Other foods that have the same effect include anise seed, carrots, dill, fennel, fig, and parsley. When citrus juice interacts with ultraviolet light, it can cause a chemical reaction on your skin, explains Dr Mona A Gohara, a dermatologist in Connecticut. The result is usually a pink, red, or purple patch on your skin. So how do you treat it? Keep the area very well lubricated with Vaseline or another ointment, especially if it’s a blister. There’s no need for an antibiotic ointment, Dr Gohara says. If you have a bad reaction, doctors can prescribe a strong hydrocortisone cream. Either way, the reaction isn’t dangerous and does heal over time. For brown spots that linger, there are prescription bleaching agents, though they should fade on their own. But Gohara recommends applying a broad spectrum SPF 30 or higher at least every two hours. If not, the brown patches can get darker and more permanent if you don’t protect yourself from the sun. If you want to avoid it to begin with, be sure to wash any food or fruit juice residue off your skin with soap and water before heading out in the sun. And don’t mix drinks outside unless you’re in a covered area. You should also watch out for any spills that may have gotten on your arms or legs. Also remember, if you’re putting lemon juice in your hair, for example, make sure to clean off your face before sunning. Says Dr Gohara, you should enjoy yourself outside and make food or drinks with citrus – just wash your hands right away.