Variety of factors — ranging from emotional stress and trauma to streptococcal infection — can cause an episode of psoriasis. Recent research indicates that some abnormality in the immune system is the key cause of psoriasis. As many as 80% of people having flare-ups report a recent emotional trauma, such as a new job or the death of a loved one. Most doctors believe such external stressors serve as triggers for an inherited defect in immune function.
Injured skin and certain drugs can aggravate psoriasis, including certain types of blood pressure medications (like beta blockers) and the anti-malarial medication hydroxychloroquine.
Psoriasis tends to run in families, but it may be skip generations; a grandfather and his grandson may be affected, but the child’s mother never develops the disease. Although psoriasis may be stressful and embarrassing, most outbreaks are relatively harmless. With appropriate treatment,symptoms generally subside within a few months.
The exact cause remains unknown. There may be a combination of factors, including genetic predisposition and environmental factors. It is common for psoriasis to be found in members of the same family. The immune system is thought to play a major role. Despite research over the past 30 years looking at many triggers, the “master switch” that turns on psoriasis is still a mystery.
Psoriasis typically starts or worsens because of a trigger that you may be able to identify and avoid. Factors that may trigger psoriasis include:
- Infections, such as strep throat or thrush
- Injury to the skin, such as a cut or scrape, bug bite, or a severe sunburn
- Cold weather
- Heavy alcohol consumption
- Certain medications — including lithium, which is prescribed for bipolar disorder; high blood pressure medications such as beta blockers; antimalarial drugs; and iodides
Anyone can develop psoriasis, but these factors can increase your risk of developing the disease:
- Family history. Perhaps the most significant risk factor for psoriasis is having a family history of the disease. About 40 percent of people with psoriasis have a family member with the disease, although this may be an underestimate.
- Viral and bacterial infections. People with HIV are more likely to develop psoriasis than people with healthy immune systems are. Children and young adults with recurring infections, particularly strep throat, also may be at increased risk.
- Stress. Because stress can impact your immune system, high stress levels may increase your risk of psoriasis.
- Obesity. Excess weight increases your risk of inverse psoriasis. In addition, plaques associated with all types of psoriasis often develop in skin creases and folds.
- Smoking. Smoking tobacco not only increases your risk of psoriasis but also may increase the severity of the disease. Smoking may also play a role in the initial development of the disease.