Mayo Clinic dermatologist Dr. Dawn Davis says the sun can cause a variety of reactions when it comes in contact with your skin. Some skin conditions prompted by sun exposure are rare; yet, others happen frequently, especially in summer.

This time of year, many of us head outside to enjoy the sunshine. Now, we all know it’s important to wear sunscreen to prevent sunburn, which is linked to skin cancer. But Davis says there are other issues that can happen from being in the sun that you might not know about.

“The sun is an immune system stimulant,” she says. “It is technically toxic to the skin and irritates the skin.”

It can trigger what’s called polymorphic light eruption, which can cause a nasty rash. It’s like an allergic reaction. Also, sun can interact with stuff on your skin, such as perfume or spilled citrus juice, and cause what looks like a burn or sting.

“Phytophotodermatitis, which is a chemical toxic reaction to the skin, which gives your skin a chemical burn,” she says.

Ouch. So be careful, because the sun can cause more trouble than just sunburn.

Davis says in addition to polymorphic light eruption and phytophotodermatitis, the following two other conditions may occur as a result of exposure to the sun: solar urticaria, which is a rare condition that causes you to be allergic to ultraviolet light, and most common for adults with lifelong high ultraviolet (UV) exposure, such as airline pilots or professional mountain climbers, and porphyria, which is a blood condition that is exacerbated by UV light, and often underdiagnosed or misdiagnosed.