Lupus develops when your immune system attacks your own tissues, but scientists still don't fully understand why this happens in some people and not others

Lupus is not something you catch from another person or inherit as a certainty. Instead, it appears to result from a combination of factors: genes that make your immune system more reactive, environmental triggers that set off that reactivity, and possibly hormonal influences. Someone with a parent or sibling who has lupus faces higher odds of developing it than the general population, but many people with a family history never develop the disease. Similarly, people without any family history can develop lupus. The condition emerges when multiple conditions align in ways researchers are still working to understand.

The core problem in lupus is a breakdown in immune tolerance—the system's ability to distinguish between threats and the body's own cells. In lupus, B cells and T cells (white blood cells that normally protect you) begin producing antibodies that attack your own DNA, proteins, and cell components. This autoimmune attack causes inflammation in joints, skin, kidneys, heart, lungs, and other organs. Why this tolerance breaks down remains an active area of research, with no single cause identified.

Key Takeaways

  • Lupus is not contagious and cannot be passed from one person to another through contact or exposure.
  • Having a close relative with lupus increases your risk, but most people with a family history do not develop the disease.
  • Environmental triggers—such as sun exposure, infections, certain medications, or physical stress—may activate lupus in people genetically predisposed to it.
  • Women are diagnosed with lupus far more often than men, suggesting hormones play a role in who develops the disease.
  • Lupus is not caused by lifestyle choices, diet, or anything you did or did not do before symptoms appeared.

Genetic factors that increase lupus risk

If you have a parent, sibling, or child with lupus, your risk of developing it is higher than someone with no family history. Studies of identical twins show that when one twin has lupus, the other develops it roughly 25 to 50 percent of the time—meaning genetics loads the gun, but something else pulls the trigger. Researchers have identified over 70 genetic variants associated with lupus risk, many of them involved in how immune cells communicate and regulate themselves.

These genetic variations are common in the general population, which is why most people who carry them never develop lupus. Instead, they appear to create a predisposition—a higher baseline likelihood that environmental or hormonal factors will tip the balance toward autoimmunity. Certain genetic patterns are more common in people of African, Hispanic, Asian, and Native American descent, which partly explains why lupus is diagnosed more frequently in these groups. Genetic testing for lupus risk is not routinely done, because carrying the genes does not mean you will develop the disease.

Environmental triggers that may activate lupus

Environmental exposures appear to play a major role in whether someone with genetic predisposition actually develops lupus. Ultraviolet (UV) light from the sun is the most well-documented trigger. People with lupus often report that sun exposure worsens their symptoms, and some develop lupus flares specifically after time in the sun. The mechanism is not fully clear, but UV light may damage skin cells in ways that expose the immune system to self-antigens—fragments of your own cells that the immune system then attacks.

Infections are another suspected trigger. Viral infections in particular—including Epstein-Barr virus (which causes mononucleosis), cytomegalovirus, and others—have been studied as potential catalysts. The theory is that the immune response to the virus may cross-react with your own tissues, or that the infection may disrupt immune tolerance. Certain medications, particularly those used to treat high blood pressure and heart rhythm problems, can trigger a lupus-like syndrome in susceptible people. Physical or emotional stress, smoking, and silica dust exposure have also been associated with lupus development, though the evidence is stronger for some triggers than others.

Why women are diagnosed with lupus much more often than men

Lupus is diagnosed in women roughly 9 to 10 times more often than in men, and this disparity points strongly to a hormonal component. The disease most commonly appears during women's reproductive years (ages 15 to 45), when estrogen levels are highest. Pregnancy can trigger lupus onset in some women, and lupus flares often worsen during pregnancy or after delivery. Oral contraceptives and hormone replacement therapy have been associated with increased lupus activity in some studies, though the relationship is complex and not universal.

Men with lupus tend to develop more severe disease and experience worse outcomes, suggesting that estrogen may actually be protective in some ways or that men's immune systems respond differently to the same triggers. The exact mechanism of estrogen's role remains unclear. It may enhance B cell survival, increase autoantibody production, or affect how immune cells communicate. This hormonal influence is one reason why lupus risk changes across a woman's lifespan—it may decrease after menopause when estrogen levels drop, though this varies by individual.

Why lupus is not caused by lifestyle or personal choices

Lupus is not caused by diet, exercise habits, stress management, sleep patterns, or any lifestyle factor you can control. It is not a result of something you did or did not do before symptoms appeared. This is an important distinction because autoimmune diseases are sometimes misunderstood as preventable through better habits. While managing stress, getting adequate sleep, and avoiding sun exposure may help reduce flares once lupus is present, these actions cannot prevent lupus from developing in someone genetically predisposed to it.

Similarly, lupus is not contagious. You cannot catch it from someone who has it, and you cannot transmit it to others. It is not caused by poor hygiene, environmental pollution you were exposed to, or any infection you contracted. The disease emerges from internal immune system dysfunction combined with genetic predisposition and environmental factors—not from external causes you could have avoided.

What happens after lupus develops

Once lupus begins, the course varies widely. Some people experience a single flare and then long periods of remission or mild symptoms. Others have frequent flares with varying severity. The unpredictability is part of what makes lupus challenging—there is no way to predict whether your disease will be mild or severe, or how it will progress over time. Factors that influence severity include which organs are affected, how early the disease is caught and treated, and individual differences in immune response.

Early diagnosis and treatment can significantly affect outcomes. People who receive treatment soon after symptoms begin tend to have better long-term kidney function and lower rates of organ damage. This is why recognizing early signs—persistent joint pain, facial rash, fatigue, or photosensitivity—and seeking medical evaluation matters. Once lupus is diagnosed, working with a rheumatologist to manage the disease and monitor for complications becomes the focus, rather than trying to prevent something that has already begun.

Frequently Asked Questions

Can you develop lupus at any age?

Lupus most commonly appears between ages 15 and 45, but it can develop at any age. Children can develop lupus, and some people first experience symptoms after age 50. Age of onset does not appear to change the underlying cause—genetic predisposition combined with environmental and hormonal factors.

If my mother has lupus, will I definitely get it?

No. Having a parent with lupus increases your risk compared to the general population, but most children of people with lupus do not develop the disease. Your risk depends on which genes you inherited and whether you encounter environmental triggers that activate those genes.

Can lupus skip generations in a family?

Yes. You can inherit genetic predisposition from a grandparent or other relative even if your parents do not have lupus. Lupus may appear in one generation, skip the next, and reappear in a third—or it may never develop in some family members who carry the same genes.

Does getting an infection cause lupus?

Infections may trigger lupus in people already genetically predisposed, but they do not cause lupus in people without that predisposition. Most people who have viral infections never develop lupus, even if they carry genetic risk factors.

Can you prevent lupus if it runs in your family?

There is no proven way to prevent lupus. If you have a family history, you cannot stop the disease from developing through lifestyle changes. However, if you do develop lupus, managing sun exposure and stress may help reduce flare severity once the disease is present.