From backyard gardening to adventurous hikes, summer offers plenty of opportunities to enjoy the sun — especially during the COVID-19 pandemic, when experts recommend gathering outdoors instead of indoors to reduce the spread of the virus. But for some people with autoimmune diseases, the sun can trigger flares and make symptoms worse.

“I’ve had patients come back from vacations in Hawaii and all of a sudden they have lupus,” says Jeffrey Carlin, MD. “And others where it's taken months to get their disease back in check after a severe sunburn.”

Dr. Carlin treated lupus patients for nearly three decades at Virginia Mason and now conducts lupus research at Benaroya Research Institute at Virginia Mason (BRI). We recently asked him how and why the sun can trigger autoimmune disease flares. Here’s what he had to say.

What autoimmune diseases cause sun sensitivity?

Scientists are still learning about the connection between sunlight and autoimmune disease flares. So far, the clearest data is related to the connection between lupus and sun exposure. Researchers know that the sun can trigger lupus in some people who were already on track to get the disease. Sun can also cause lupus flare-ups in people who already have the disease. 

There is also some evidence of a connection between sunlight and flares of a disease called dermatomyositis. Research suggests that severe sunburn might also trigger flares of psoriasis and scleroderma. Scientists are still working to learn more about this.

“We don’t typically see these sun-related flares with diseases like rheumatoid arthritis (RA) and inflammatory bowel disease,” Dr. Carlin says. “That said, we do know that some RA medications may make patients sensitive to light.”

Dr. Carlin explains that too much UV exposure can be toxic for anyone. When you get a bad sunburn, the sun kills cells on the surface of your skin. Then your body gets rid of these cells by basically telling them to die in a process called apoptosis.

“During apoptosis, cells essentially self-destruct,” Dr. Carlin says. “Then there’s an immune response where white blood cells come in and chew them up — this is when some people get red and peel. Then new, healthy cells grow in their place.”

But people with lupus (and every autoimmune disease) have overactive immune systems. So when people with lupus get exposed to the sun and their cells “spill their guts,” it may trigger an immune reaction that’s too strong.

“White blood cells get turned on, other immune cells get turned on, and pretty soon you have a total flare of your immune system — it's like throwing gasoline on a fire,” Dr. Carlin says. “We see many people with lupus get skin rashes and even kidney problems as their immune cells go into overdrive and attack healthy tissue.”

For some people, these symptoms go away on their own, while others require treatments that help calm down the immune system.

Enjoying the Sun with Autoimmune Disease

Juana and Diane don’t let their sun sensitivities stop them from enjoying time outside. Diane — who loves the outdoors and can’t wait to plan more beach vacations when the pandemic is over — learned to change her wardrobe after her lupus diagnosis.

“I’ve started wearing long sleeves, and staying out of direct sunlight as much as possible when I go hiking or running,” Diane says.

Juana also dresses strategically, rather than missing out on time outside.

“If I’m going to the park, I’ll wear long sleeves, long pants and a big floppy hat,” she says. “I also bring a scarf to cover my face if I need to.”

Dr. Carlin recommends being strategic about your sunscreen and remembering to reapply. Many makeup and skincare products can also provide UVA/UVB protection. If you wear makeup, using those products can be an easy way to make sunscreen part of your routine.

“Not all sunscreens are made equal,” Dr. Carlin says. “I recommend using at least SPF 50 and checking the label to make sure it protects you from UVA and UVB rays.”

He also recommends choosing clothing that offers higher sun protection, like those made from thicker materials and darker fabrics. You can also wash your clothes in a solution that makes them more UV resistant, which you can buy from a handful of brands at box stores and online.

“I tell my patients, you don’t have to turn into a vampire,” Dr. Carlin says. “Being careful and smart about your sun exposure can help you enjoy the outdoors without triggering disease flares.”