If you’re living with psoriasis, you may wonder why you developed the skin condition. Psoriasis is a disease in which the immune system is triggered and mistakenly attacks its own cells and tissues. Researchers don’t have a clear understanding of why this immune system dysfunction happens in psoriasis, and there’s no single cause for the condition. However, they have discovered several factors that increase a person’s risk of developing psoriasis.

Normally, immune cells called T cells are responsible for attacking invaders like bacteria and viruses. In psoriasis, T cells attack your skin, and in psoriatic arthritis (PsA), they attack the joints. At the same time, the body releases cytokines and other proteins that cause inflammation — discoloration, swelling, pain, and heat — in areas where the disease is active.

As a result of autoimmune attacks, the body produces new skin cells at a faster rate. People without psoriasis replace their skin cells about once a month, shedding old cells as they are replaced. In psoriasis, skin cells are replaced every few days, but they can’t be shed quickly, resulting in the buildup of thick, scaly skin, as seen in plaque psoriasis.

Psoriasis involves multiple risk factors, and varying circumstances can trigger it. Learn more about the risk factors for psoriasis and common flare triggers.

1. Family History

Research shows that people with a family history of psoriasis have an increased risk of developing the condition. One study found that people who had a sibling with psoriasis were four to six times more likely to develop it.

According to the National Psoriasis Foundation, if a parent has psoriasis, their child has a 28 percent chance of also developing psoriasis. That risk shoots up to 65 percent if both parents have psoriasis. However, some people with psoriasis have no family history of the disease.

2. Genetics

Because scientists have found patterns of psoriasis within families, they’ve questioned whether the condition has a genetic component. So far, researchers have found that several loci (locations of a gene on a chromosome) are associated with the development of psoriasis. One of these is the PSOR1 locus. Scientists have also found specific genes and associations between genes that may play a role in psoriasis.

Some of the genes linked to the development of psoriasis include HLA-C, IL23A, IL12B, TNIP1, HBD, and HLA-Cw6, according to the journal Trends in Genetics. Research studies have found that nearly 46 percent of people with plaque psoriasis have the HLA-Cw6 gene, compared to only 7.4 percent of people without psoriasis.

Not everyone with HLA-Cw6 or other psoriasis-associated genes will develop psoriasis. However, for someone with a genetic predisposition to psoriasis, changes in the immune system and environmental factors can cause symptoms. A genetic predisposition means that because of your genes, you have a higher chance of having or developing a particular trait or condition.

People with psoriasis or psoriatic arthritis also have a higher risk of other ongoing conditions or comorbidities (two or more conditions at the same time), including:

• Type 2 diabetes
• Cardiovascular disease (heart and blood vessel disease)
• Crohn’s disease
• Ulcerative colitis
• Hypertension (high blood pressure)

Psoriasis does not cause these conditions, but these diseases may share underlying genetic risk factors.

3. Smoking

Smoking tobacco raises the risk of psoriasis. A 2020 meta-analysis found that people who smoked in the past or currently smoke had a higher risk of psoriasis than did people who had never smoked. According to Mayo Clinic, smoking tobacco can also make psoriasis worse.

If you smoke tobacco and have psoriasis, it’s hard to say whether smoking was the only cause of your psoriasis. However, quitting smoking may help you better manage symptoms of the skin disease.

Studies have shown a strong connection between smoking and palmoplantar psoriasis. Palmoplantar psoriasis causes discolored, scaly patches to develop on the palms of the hands and the soles of the feet.

4. Infections

Infections, including those caused by bacteria such as Streptococcus (the cause of strep throat), are known to trigger flares in people with psoriasis. Some scientists believe that strep infections set off the initial immune reaction that causes psoriasis to develop. If someone has a genetic tendency for psoriasis triggered by infections, they might have flare-ups with a strep throat infection.

The link between upper respiratory infections and guttate psoriasis is the most well-established, according to the International Journal of Molecular Sciences. Guttate psoriasis is a type of psoriasis in which small, discolored, scaly spots appear on the skin. It often occurs after a bacterial infection, like strep throat, and can go away on its own over time. Strep infections affect the immune system and are known to cause similar autoimmune attacks in rheumatic heart disease and kidney disease.

Other infections that have been found to trigger psoriasis flares include:

• Human papillomavirus (HPV)
• Staphylococcus aureus (staph) infection
• Helicobacter pylori
• Human immunodeficiency virus (HIV)
• Hepatitis B virus
• Hepatitis C virus
• Malassezia and Candida yeasts

Although scientists have observed connections between infections and psoriasis flare-ups, the exact way in which infections trigger psoriasis symptoms is not well understood.

5. Higher Body Weight

There is a connection between having a body mass index (BMI) of 35 or higher and developing psoriasis. Scientists are uncertain whether having a higher body weight increases a person’s risk of psoriasis or whether having psoriasis raises the risk of a higher weight.

Both higher body weight and psoriasis share a common factor of inflammation. Epidemiology studies have also found that the severity of psoriasis symptoms increases as BMI increases. An epidemiology study is a kind of research that focuses on the patterns, causes, and effects of health-related events and conditions within populations.

Flare Triggers for Psoriasis

Psoriasis and psoriatic arthritis can go into remission — periods of minimal or no symptoms. A remission can last for months or years until the next disease flare-up. Many situations can trigger flares of psoriasis and PsA symptoms.

Some flare triggers are also being researched as possible causes of psoriasis, but most aren’t thought to cause the disease itself. Flare triggers are conditions that increase inflammation and stimulate autoimmune attacks, bringing new or worse psoriasis symptoms.

The triggers for psoriasis can vary from person to person. Common triggers include:

• Emotional stress
• Cigarette smoking
• Viral, bacterial, or fungal infections
• Alcohol consumption
• Cold, dry weather
• Some medications, including common blood pressure drugs, lithium, and antimalarial drugs
• Skin injuries such as sunburns and cuts

If you need help identifying and avoiding your psoriasis triggers, talk to your dermatology provider. In addition to helping treat your psoriasis, they can give you information and advice to help prevent flare-ups. They can also provide you with resources for smoking cessation programs.

Is Psoriasis Contagious?

Psoriasis is not contagious. You can’t catch it by touching someone with psoriasis, even during a flare with a visible rash. Many people mistakenly believe that psoriasis is contagious because they don’t know enough about the condition. This misunderstanding can lead to unfair treatment and isolation for individuals living with psoriasis. It’s important to educate others and raise awareness about psoriasis to counter these negative attitudes and create a supportive community for those affected by the condition.

Find Your Team

MyPsoriasisTeam is the social network for people with psoriasis and their loved ones. On MyPsoriasisTeam, more than 134,000 members come together to ask questions, give advice, and share their stories with others who understand life with psoriasis.

Have you been diagnosed with psoriasis? Have you noticed family history or other risk factors influencing your condition? Share your experience in the comments below, or start a conversation by posting on your Activities page.