Psoriasis is not something you catch—it develops when your immune system misfires

Psoriasis happens when your immune system attacks your skin cells by mistake. Your body's defense system normally protects you from infection, but in psoriasis, it treats your skin as a threat and speeds up the growth cycle of skin cells. This causes cells to pile up faster than your body can shed them, creating the thick, scaly patches that define the condition. You cannot catch psoriasis from another person, and you do not develop it because of poor hygiene or lifestyle choices alone.

The exact trigger varies from person to person. Some people inherit a genetic tendency toward psoriasis—if one parent has it, your risk is higher. Others develop it after a specific event: a serious infection, a skin injury, certain medications, or prolonged stress. Many people have the genetic predisposition but never develop psoriasis unless one of these triggers occurs. This is why two siblings with the same family history may have very different outcomes.

Key Takeaways

  • Psoriasis develops when your immune system mistakenly attacks skin cells, causing them to multiply much faster than normal.
  • Genetics play a major role—if your parents or close relatives have psoriasis, your risk is significantly higher.
  • Common triggers include strep throat and other infections, skin injuries, certain blood pressure or heart medications, and periods of high stress.
  • You cannot catch psoriasis from someone else, and it is not caused by poor hygiene or diet alone, though these factors may influence flare-ups.

How genetics increase your psoriasis risk

If psoriasis runs in your family, your body may carry genes that make your immune system more likely to overreact to triggers. Research shows that if one parent has psoriasis, roughly one in three children will develop it at some point. If both parents have it, the risk rises to about two in three. However, having these genes does not may provide you will develop psoriasis—many people inherit the tendency but never experience symptoms.

The genetic link explains why psoriasis often appears to "run in families" but does not follow a simple pattern. You might inherit the susceptibility from a grandparent whose psoriasis was mild or appeared late in life, making the connection less obvious. Genetic testing is not routinely done for psoriasis because the condition involves multiple genes, not just one, and environmental triggers matter as much as genetics.

Infections that can trigger psoriasis

Strep throat is the most common infection linked to psoriasis onset, particularly in children and young adults. The infection can trigger an immune response that persists even after the strep infection clears, leading to psoriasis weeks or months later. Other bacterial infections, including skin infections and respiratory infections, have also been associated with psoriasis development or flare-ups.

Viral infections like HIV and certain herpes viruses may also play a role. If you notice psoriasis appearing or worsening after a serious infection, mention this timing to your doctor—it helps them understand your condition and may affect how they monitor you over time.

Skin injuries and the Koebner response

Psoriasis can develop or worsen at sites of skin injury, a pattern called the Koebner response. This means that cuts, burns, surgical wounds, tattoos, or even severe sunburn can trigger psoriasis to appear in that exact location, usually within one to two weeks. The injury itself does not cause psoriasis, but it can activate the condition in someone whose immune system is already primed for it.

This is why people with psoriasis are often advised to avoid unnecessary skin procedures and to protect their skin from injury when possible. If you have psoriasis and need surgery or a tattoo, tell the provider beforehand so they can take extra care to minimize trauma to your skin.

Medications that may trigger or worsen psoriasis

Certain medications can trigger psoriasis or cause existing psoriasis to flare. The most common culprits are beta-blockers (used for high blood pressure and heart conditions), lithium (used for bipolar disorder), and nonsteroidal anti-inflammatory drugs like ibuprofen and naproxen. Antimalarial drugs and ACE inhibitors for blood pressure can also trigger flares in some people.

If you take any of these medications and develop psoriasis, or if your psoriasis worsens after starting a new medication, do not stop taking it without talking to your doctor first. Your doctor may be able to switch you to an alternative that does not trigger psoriasis, or they may recommend additional psoriasis treatment to manage the condition while you continue the necessary medication.

Stress and psoriasis flare-ups

Psychological stress is one of the most frequently reported triggers for psoriasis flares. High stress activates your immune system and raises inflammation throughout your body, which can cause psoriasis to appear or worsen. The relationship works both ways: stress can trigger psoriasis, and having psoriasis can create stress, which then worsens the condition further.

This does not mean psoriasis is "all in your head" or that you caused it by worrying. Stress creates measurable changes in your immune function and hormone levels. Managing stress through exercise, sleep, relaxation techniques, or counseling may help reduce flare frequency, though it cannot prevent psoriasis entirely if you have the genetic predisposition.

Other factors that influence psoriasis development

Climate and weather can affect psoriasis risk and severity. Many people find their psoriasis improves in summer with more sunlight and worsens in winter with less sun exposure and dry indoor air. Smoking and heavy alcohol use are associated with more severe psoriasis and may increase the risk of developing the condition. Obesity has also been linked to higher psoriasis risk, though the exact mechanism is still being studied.

Hormonal changes can trigger psoriasis in some people. Women may notice psoriasis appearing or worsening during puberty, pregnancy, or menopause. These factors do not cause psoriasis on their own but may act as triggers in people with genetic susceptibility.

Frequently Asked Questions

Can you get psoriasis from touching someone who has it?

No. Psoriasis is not contagious. You cannot catch it from skin-to-skin contact, sharing towels, or any other direct contact with someone who has psoriasis. It develops only in people whose immune system is primed to react this way, usually because of genetics and a specific trigger.

If my parent has psoriasis, will I definitely get it?

Not necessarily. Having a parent with psoriasis increases your risk significantly, but many people with a family history never develop the condition. You may carry the genetic tendency without ever encountering a trigger that activates it, or your triggers may be mild enough that psoriasis never appears.

Can diet cause psoriasis?

Diet alone does not cause psoriasis, but certain foods may trigger flares in some people. Common triggers include alcohol, spicy foods, and foods high in inflammatory compounds. Keeping a food diary can help you identify whether specific foods worsen your psoriasis, but this varies widely from person to person.

Does psoriasis develop suddenly or gradually?

Psoriasis can appear suddenly after a trigger like an infection or injury, or it can develop gradually over weeks or months. Some people have their first outbreak in childhood, others in adulthood. The speed of onset does not predict how severe the condition will be or how it will respond to treatment.

Can you prevent psoriasis if it runs in your family?

You cannot prevent psoriasis if you have the genetic predisposition, but you may reduce flare frequency by managing known triggers: avoiding unnecessary skin injuries, managing stress, protecting your skin from extreme weather, and treating infections promptly. If you take a medication known to trigger psoriasis, talk to your doctor about alternatives before symptoms appear.