The cause of lupus is unknown. Scientists have proven that lupus is autoimmune in origin. 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.

• Gender — Women are 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 — Researchers have found that lupus is more prevalent among nonwhite people than white people.
• 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.

Although many genes are involved in a person’s risk of developing lupus, the condition doesn’t appear to be directly inherited from one’s parents in any clear genetic pattern. 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 lupus is between 0.05 percent and 0.1 percent. However, if a person has a first-degree relative (like a parent, sibling, or child) with the disease, the risk is 17 times higher. In identical twins, if one twin is diagnosed with lupus, 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 also influences a person’s risk of developing lupus. According to the Lupus Foundation of America, “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 lupus than white women. In addition to being more likely to develop the disease, people of different racial and ethnic groups may experience symptoms differently.

Hormonal Factors

Lupus affects women more than men. Women are nine times more likely than men to develop lupus, according to the National Resource Center on Lupus. In general, autoimmune diseases affect women at much higher proportions than men. According to Nature Reviews Immunology, “80 percent of autoimmune disease occurs in females.” Women’s immune systems are believed to be more effective than men’s, giving women greater protection from infections but making them more vulnerable to autoimmune disorders.

Hormones such as estrogen, which women produce in a much higher proportion than men, may also influence the risk of developing lupus. In many women, lupus tends to flare during menstruation and pregnancy, when hormone levels are highest.

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 (SLE), the most common type of lupus that affects many organs.

Several studies have found an association between people who have had mononucleosis (or “mono”). This disease is caused by the Epstein-Barr virus (EBV). The thought is that EBV can trigger the immune system to make proteins called autoantibodies that cause inflammation. A 2017 study found that more than two-thirds of people with lupus 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.

Medication

Certain medications have been associated with drug-induced lupus — a form of the condition caused by specific prescription medications. The medications that cause drug-induced lupus are usually used to treat chronic conditions, meaning people generally take them over a long period of time.

In general, the symptoms of drug-induced lupus are not as severe as SLE. The symptoms are distinct from other side effects of the medication and usually go away shortly after the medication is stopped.

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

• Procainamide, used to treat irregular heartbeat
• Hydralazine, used to treat high blood pressure
• 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:

• Traumatic injury
• Giving birth
• Death of a loved one
• Divorce
• Surgery

Exposure to Toxins

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

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

Prevention

There is no way to prevent lupus, but if you are aware of your personal risk factors, you may be able to avoid 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 treatment plan to help avoid complications of lupus, like damage to internal organs, lupus nephritis, and osteoporosis.

Condition Guide

• Lupus – An Overview
• Symptoms of Lupus
• Lupus — The Path to Diagnosis
• Treatments for Lupus
• Types of Lupus