The exact cause of lupus remains unknown, but scientists have confirmed that it is an autoimmune disease. In other words, the damage in lupus is caused by the body’s immune system attacking its own tissues. However, researchers have not yet solved the puzzle of why this process begins.

Although researchers have established links between certain factors and a person’s risk for developing lupus, none have identified why some people get lupus and some don’t. Most scientists believe the condition is most likely caused by a combination of hereditary, hormonal, and environmental factors.

Risk Factors

Scientists have identified many risk factors for lupus and continue to study them, but they haven’t pinpointed any as the cause of the condition. It is important to note that while science is good at finding correlations, or apparent relationships, between factors and disease, correlation does not prove that the factor causes the disease.

Although the cause of lupus is unknown, certain factors may increase a person’s risk of developing the disease.

• Sex and gender — Women are far more likely than men to develop lupus, according to the Centers for Disease Control and Prevention (CDC). The Lupus Foundation of America notes that 90 percent of people living with lupus are women.
• Age — Most people are diagnosed with lupus between the ages of 15 and 45.
• Race and ethnicity — According to the Lupus Foundation of America, “lupus is two to three times more prevalent among African American, Hispanic/Latina, Asian American, Native American, Alaska Native, Native Hawaiian and other Pacific Islander women than among White women.”
• Family history — People with relatives living with lupus are more likely to develop the disease themselves.

Hereditary Factors

Scientists have identified more than 100 genetic variants involved in the body’s immune response that are more prevalent in people living with lupus. Still, more research is needed to understand how inherited genes can make a person more susceptible to the condition.

While many genes contribute to a person’s risk of developing lupus, the condition is not typically inherited in a straightforward genetic pattern. Lupus is a complex disease, influenced by multiple genes. Some of these have been identified to increase the response to environmental factors like exposure to sunlight. Studies show that the relatives of people with lupus have a higher chance of developing the disease themselves.

In the U.S., the prevalence of systemic lupus erythematosus (SLE) — the most common form of lupus that affects many organs — is between 0.05 percent and 0.1 percent. This means around 165,000 to 330,000 people in the U.S. have SLE. If a person has one first-degree relative (such as a parent, sibling, or child) with SLE, their risk of developing the disease is about 17 times higher compared to the general population, according to research in JAMA Internal Medicine . If they have more than one first-degree relative with SLE, their risk increases to approximately 35 times higher.

In identical twins, if one twin is diagnosed with SLE, the chances of the other twin developing the condition is between 24 percent and 40 percent, according to Frontiers in Immunology .

A person’s risk for lupus also increases if one or more of their family members have other autoimmune diseases, such as rheumatoid arthritis, Crohn’s disease, ulcerative colitis, or multiple sclerosis.

Race and Ethnicity

Race and ethnicity also influences a person’s risk of developing lupus. According to the Lupus Foundation of America, “In the United States, lupus is more common in people of color than in the Caucasian population. This includes African Americans, Hispanics/Latinos, Asian Americans, Native Americans, Native Hawaiians and Pacific Islanders.” A 2016 study from Arthritis Rheumatology found that Black women were more than three times as likely to be diagnosed with SLE than white women.

A person’s racial and ethnic background may also affect how they experience lupus symptoms. According to research in Rheumatology, Black, East Asian, South Asian, and Hispanic individuals with SLE are more likely to develop symptoms at a younger age. Compared to white people, they are also more likely to have a more severe disease course, including a greater number of manifestations (such as involvement of multiple organs like the kidneys, heart, and skin) and more rapid damage accumulation.

Hormonal Factors

Women are nine times more likely than men to develop lupus, according to the National Resource Center on Lupus. The risk for SLE is highest among women of childbearing age (15 and 44), according to the Centers for Disease Control and Prevention (CDC). In general, “80 percent of autoimmune disease occurs in females,” according to Nature Reviews Immunology. Women’s immune systems are similar to men’s but generally respond more strongly to infections, according to Clínic Barcelona. This helps protect women from infections but also makes them more prone to developing autoimmune disorders.

Hormones like estrogen may influence the risk of developing lupus. According to the Lupus Foundation of America, females produce estrogen at higher levels than males. Some people experience SLE flares during menstruation and pregnancy, when hormone levels are higher, though research on this is mixed. The decrease in lupus activity after menopause suggests that hormones play a role in the disease.

Environmental Factors

Researchers have identified many environmental triggers linked to the development of lupus.

Viral Infection

Scientists have investigated specific viruses for links with systemic lupus erythematosus.

Several studies have found an association between Epstein-Barr virus (EBV) infections, such as mononucleosis (“mono”), and an increased risk of developing lupus. Researchers suggest that EBV may trigger autoantibody production, leading to inflammation. A 2017 study in the Asian Pacific Journal of Cancer Prevention found that more than two-thirds of people with SLE also had EBV.

Other viruses can pave the way for developing lupus by causing genetic changes in some people. These viruses include herpes zoster (responsible for chickenpox and shingles) and cytomegalovirus.

Medications

Certain medications have been associated with drug-induced lupus — a form of the condition caused by specific prescription medications. Medications that can cause drug-induced lupus are often prescribed for chronic conditions and are typically taken over extended periods.

Symptoms of drug-induced lupus are generally milder than those of systemic lupus erythematosus, and they usually go away shortly after the medication is stopped.

The most common medications associated with drug-induced lupus include:

• Isoniazid, used to treat tuberculosis
• Hydralazine, used to treat high blood pressure
• Procainamide, used to treat irregular heartbeat
• Tumor necrosis factor (TNF) alpha inhibitors, such as etanercept, infliximab, and adalimumab, used to treat autoimmune conditions
• Minocycline, used to treat acne and bacterial infections
• Quinidine, used to treat irregular heartbeat

Exposure to Ultraviolet Light

Exposure to ultraviolet (UV) light (e.g., sunlight, fluorescent lights, tanning beds) is known to trigger lupus flare-ups in many people. Scientists theorize that ultraviolet light can trigger an inflammatory response in some people. Exposure to higher ultraviolet light is associated with a higher risk of developing SLE. Certain antibiotics increase photosensitivity (sensitivity to light) and may increase the risk of developing lupus as well.

Stress

Physical and emotional stress are well-known flare triggers that some researchers believe encourage lupus to develop. Many people experience their first lupus symptoms after stressful events such as:

• Experiencing a traumatic injury
• Giving birth
• Losing a loved one
• Getting divorced
• Undergoing surgery

Exposure to Toxins

Scientists suspect a variety of toxins may trigger the development of lupus. These include:

• Silica dust (a compound found in quartz rock and a common byproduct of many industries)
• Pesticides
• Cigarette smoke
• Mercury

Body Weight

Some studies report an increased incidence of SLE in people with obesity, defined as a body mass index (BMI) of 30 or higher, which is calculated using a person’s height and weight. However, this association has not been consistently observed across all racial and gender groups.

Nutritional Factors

People with SLE tend to have lower levels of vitamin D compared to those without the condition. However, it remains unclear whether low vitamin D levels contribute to the development of lupus or are a result of the disease.

Smoking

People who smoke have a higher risk of developing SLE compared to those who have quit or never smoked. Smoking exposure has also been associated with increased disease activity and greater long-term damage in people with SLE.

Psychosocial Stressors

Studies have shown a higher risk of SLE in people with a history of depression, post-traumatic stress disorder (PTSD), and childhood abuse (physical/emotional/sexual).

Can Lupus Be Prevented?

While lupus cannot be prevented, awareness of personal risk factors may help you avoid potential triggers.

You can take these steps to avoid triggers:

• Limit your time in direct sunlight and wear sunscreen.
• Quit smoking.
• Manage stress.

Watch for common symptoms of lupus such as fatigue, joint pain, or a butterfly-shaped rash on the face. A doctor specializing in diseases that affect muscles, joints, and bones — called a rheumatologist — can help make an early diagnosis using your medical history, blood tests, and imaging. You and your doctor will develop a lupus treatment plan to help avoid complications of lupus, like damage to internal organs, lupus nephritis, and osteoporosis.

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