Photosensitivity and Lupus: How Sun Exposure Affects Autoimmune Conditions

The summer months are in full swing here in the Phoenix Valley, bringing along ample sunshine and high temperatures. With the average monthly Phoenix UV index of 11.4 in July, it’s crucial to take extra care before heading outside to enjoy summer activities.

This month is UV Safety Month, and Summit Rheumatology is stressing the importance of sun safety. For those living with autoimmune conditions, the skin may be more sensitive to UV rays, a phenomenon known as photosensitivity.

So before you head outside to join in on all of the Arizona outdoor fun this summer, here’s why you may need to be extra prepared to protect your skin if you have an autoimmune condition.

How Do UV Rays Cause Damage?

Ultraviolet (UV) radiation is the natural energy emitted by the sun (it is also emitted from tanning beds and other artificial sources like nail salon lamps). The ozone layer, a section of high ozone concentration in the stratosphere, shields Earth from much of the UV radiation. The remaining UV light reaches every region of the planet, but is stronger in areas that receive more direct sunlight and at higher altitudes.

UV light can be broken into three different types based on the length of their wavelengths. UVA has a longer wavelength and is less associated with cancer than UVB (both are still carcinogenic). UVA primarily ages the skin, causing wrinkles, sunspots, and sagging. UVB has a shorter wavelength and is associated with skin cancer, including melanoma. This is also the type of UV ray that most frequently leads to sunburn.

UVC is the highest energy portion of the UV spectrum. Thankfully, UVC is blocked entirely by the ozone layer; however, artificial sources like lamps and lasers can still emit UVC. Exposure to UVC can lead to severe burns and eye injuries.

UV radiation damages skin cells, tissue, and blood vessels. Specifically, it damages cell DNA (especially UVB radiation). When the DNA of our cells are damaged or altered, this can create genetic mutations or faults in our cells that can lead to skin cancer or trigger autoimmune symptoms.

Lupus and Sunlight

UV radiation is damaging for everyone, but for people with lupus, UV radiation can also trigger flares and worsen symptoms.

The cells in individuals with lupus are extra sensitive, and it takes the body longer to replace damaged cells with new ones. When cells are damaged by UV radiation, they linger in the body longer than they would in individuals who don’t have lupus. These damaged cells send out inflammatory signals and free radicals that can trigger lupus flares. This is the primary cause of photosensitivity from lupus.

Symptoms of Photosensitivity and Lupus

Photosensitivity is not exclusive to lupus patients but is very common. According to the Lupus Foundation of America, 40% to 70% of Lupus patients experience photosensitivity. For these individuals, UV exposure can lead to a number of symptoms, including:

  • Rashes, especially a “butterfly” shaped rash across the face, and disk-shaped lesions that may leave scars
  • Joint pain
  • Fever
  • Organ inflammation

It’s easy to experience a severe burn if you have lupus, even if you aren’t experiencing symptoms at the time of sun exposure.

“Patients can exacerbate lupus symptoms by spending time out in the sun without adequate sunscreen or protective clothing, even if their lupus was previously in remission,” says Dr. Panico, DO and Chief of Rheumatology at Summit.

“Some patients may even see some of their first signs and symptoms of lupus after experiencing a bad sunburn or going on vacation where they are out in the sun more than usual. Sun protection is not just important for lupus patients with fair skin, but all skin tones can be damaged by the sun.”

Rheumatoid Arthritis and Sun Exposure

Patients with rheumatoid arthritis may also experience photosensitivity, but unlike with lupus, it isn’t associated with the underlying autoimmune condition itself. Rather, many medications commonly prescribed to treat RA can cause photosensitivity.

Medications including methotrexate, sulfasalazine, hydroxychloroquine, and NSAIDs like ibuprofen and naproxen are all associated with photosensitivity. Some of these medications may induce a phototoxic reaction: the drug is activated by UV radiation and can cause a rash similar to a sunburn. In phototoxic reactions, a rash usually appears within 24 hours of exposure.

Photoallergic reactions are also linked to certain RA medications. A photoallergic reaction occurs when UV rays structurally alter the components of the medication. This may cause the immune system to mistake the medication for an antigen and launch an attack, leading to an allergic response.

It’s important to be extra cautious if you plan to be in the sun and are currently taking any of these medications.

“I recommend SPF 50 and above to all my patients who take medications for an autoimmune condition and frequent reapplication is often needed,” says Dr. Panico.

“Living in Arizona, we often avoid the sun directly in the summer but can forget to reapply sunscreen while swimming or sitting outdoors where there are misters. Even exercising outdoors early in the morning can lead to sunburn and we should be cautious about prolonged direct sun exposure at any time of day. This is important for traveling also. We often think that if it is not hot outdoors that the sun is not causing damage — but that just is not the case if you have a medical condition or are taking a medication that can make your skin more sensitive to the sun.”

Vitamin D Levels and Risk of Developing RA

Despite the risks of unprotected sun exposure, safe sun exposure may be beneficial. In fact, there are several studies that suggest that increased sun exposure over the life course may reduce the risk of developing rheumatoid arthritis. Why? It may be because sun exposure leads to higher absorption of vitamin D.

Vitamin D deficiency has been linked to a higher rate of rheumatoid arthritis, while vitamin D deficiency in patients already diagnosed with RA has been shown to worsen symptoms. Vitamin D is thought to have an anti-inflammatory effect on the body, which may help reduce symptoms or prevent inflammatory reactions.

“Vitamin D is necessary for the proper functioning of our immune system. We are learning more about the importance of vitamin D and functions aside from bone health. It is very common to be deficient in this essential vitamin. But too much vitamin D is not good either, so the dose that someone takes should be monitored to prevent toxicity.”

In a 2013 study of a group of women, researchers saw a higher number of RA cases amongst individuals who had an overall lower average UV-B exposure. In another 2008 study surveying RA cases in the US, women in New England had a 37% to 45% elevated risk of RA compared to other regions.

The cause? Possibly climate differences, including less sun exposure than some of the more western states (behavioral factors, genetic factors, and environmental exposures cannot be ruled out as contributing factors).

Photosensitivity and Sun Protection

Individuals with photosensitivity from their medications or autoimmune conditions may need to take extra precautions before stepping outside. Here are some sun protection tips that can help keep your skin covered and prevent sun-induced flares, including photosensitivity from lupus or RA medications:

  • Wear a water-resistant, broad-spectrum sunscreen with an SPF of at least 50. Reapply every several hours, especially if you have been sweating or spent time in the water.
  • Wear sun-protective clothing with a UPF of at least 50.
  • Wear sunglasses
  • Wear wide-brimmed hats
  • Find shady spots if you are sitting outside, like under an umbrella
  • Avoid direct sunlight between 10 a.m. and 4 p.m, which is when the UV index is the highest
  • Use UV-blocking shades on your windows
  • Limit indoor lights and turn them off when they aren’t in use
  • Drive with the windows up
  • Use LED bulbs (these don’t emit UV light)
  • Avoid tanning beds and UV lamps used at nail salons

Protecting yourself from UV rays helps protect your overall health. For more information on sun protection, visit If you would like specific recommendations on sunscreen or sun care products, our rheumatology specialists can help.

Summit Rheumatology is here for you to help you manage your autoimmune condition. Our lupus and rheumatoid arthritis specialists create individualized treatment plans that fit your lifestyle to help you reach your goals.

Ready to schedule an appointment? Give us a call or send us a message.

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