The cause of systemic lupus erythematosus is unknown. It appears to be triggered in some people, by:

• sunlight,
• stress,
• viral infection,
• puberty,
• menopause,
• childbirth, or
• long-term use of some types of medication.

Hormonal factors may be involved because many more women than men are affected. Also, in women, the contraceptive pill or pregnancy may make symptoms more severe suggesting a hormonal link.

Genetic factors may be involved. SLE is more common in black and Asian women and it sometimes runs in families.