Individuals with lupus are more sensitive to UV light. As a result, UV exposure can often trigger a lupus sun rash. This exposure can occur from sunlight and certain lights or lasers.

Lupus is a chronic autoimmune disease that can cause pain and inflammation in many different parts of the body. An autoimmune disease occurs when the immune system mistakenly attacks healthy cells in the body. This is because the body cannot differentiate between healthy tissue and harmful bacteria and viruses.

Lupus symptoms can vary widely, making it a difficult condition to diagnose. A person with the condition may find that they are more sensitive to UV light. They may develop a severe skin rash after exposure to UV rays. They may also experience symptoms such as lesions, fatigue, or a fever.

In this article, we will discuss why sun exposure can cause lupus to flare and how a person can best protect themselves.

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Around 40–70% of people with lupus are prone to photosensitivity. This term describes an increased sensitivity to UV rays from the sun and other artificial light sources.

When someone with lupus experiences exposure to UV rays, it can result in a flare of their lupus symptoms. The most common symptom is a painful skin rash or lesions on areas such as the face, neck, hands, and feet.

A person with lupus and photosensitivity may also experience symptoms such as fatigue, a fever, joint pain, or flu-like symptoms, after exposure to UV light. Even minimal exposure to UV rays can cause lupus symptoms to flare.

UV light is a type of radiation that the sun and some artificial forms of light emit. UV light can cause biological reactions in the body and can lead to a flare of symptoms in someone with lupus.

UV rays damage the cells of the skin. When the cells of the skin become damaged from UV light, it causes them to die, in a process known as apoptosis. In a person without lupus, the body quickly clears the dead skin cells. Additionally, any sunburn or irritation heals within a short time.

A person with lupus may also have skin cells that are more sensitive to sun-induced damage. Their body may not be able to clear the dead skin cells away effectively. They may form immune complexes that stay in the body for longer, further triggering an immune response and leading to a lupus flare.

When a person with lupus cannot avoid exposure to UV light, there are several steps they can take to greater protect themselves. Some of these include:

  • Sunscreen: A person can liberally apply a sunscreen that protects against both UVA and UVB rays, with an SPF of 30 or above. The Food and Drug Administration (FDA) recommends reapplying sunscreen every 2 hours or more often after swimming or sweating.
  • Protective clothing: It is advisable for a person to wear tightly woven, long clothing that covers the entire body where possible. There are some clothing options available that have international standards certifications for UV protection.
  • Headwear: A hat with a wide brim that keeps the face, ears, and neck in the shade can offer suitable protection. Materials, such as canvas, can protect against UV rays, while headwear consisting of straw may have holes in them.
  • Sunglasses: Sunglasses that shield against both UVA and UVB rays can protect the eyes and skin surrounding them.
  • Sun avoidance: Where possible, individuals need to avoid sun exposure between the hours of 10 a.m. and 4 p.m., when the sun is at its strongest. A person needs to seek shade from the sun as much as possible when they go outside.
  • UV blocking shades: A person can use blocking shades over their windows to prevent sunlight from streaming in.

If a person finds they are extremely photosensitive, they may wish to choose light bulbs that have the lowest possible irradiance for their home. An individual may also want to cover halogen and fluorescent bulbs with light shields or glass that filters out UV rays.

Read more about protection against UV rays.

There are also several medications that can increase photosensitivity. Some of these include:

Additionally, the lupus medication methotrexate can also increase a person’s photosensitivity. However, if taking methotrexate helps a person manage their lupus symptoms, they can consult a doctor about the best course of action.

Conversely, a lupus medication known as hydroxychloroquine (Plaquenil) can have a positive effect on photosensitivity. Some doctors may prescribe this medication to help protect against this type of sensitivity.

A person living with lupus may experience increased sensitivity to UV light. This often results in a painful skin rash following exposure to sunlight or artificial sources of UV light.

An individual can take precautions to protect themselves from UV rays, such as frequently applying a high-SPF sunscreen, wearing protective clothing, and avoiding sun exposure between the hours of 10 a.m. and 4 p.m.

Additionally, certain medications, including those for treating lupus, can increase light sensitivity. An individual may wish to consult a doctor about alternative medications if they are experiencing side effects.