Psoriasis starts with your immune system attacking your skin cells
Psoriasis happens because your immune system mistakenly treats skin cells as a threat and speeds up their growth cycle. Normally, skin cells take about three to four weeks to move from the bottom layer to the surface and shed. In psoriasis, that process compresses to three to seven days, causing cells to pile up faster than your body can shed them. This buildup creates the thick, scaly patches you see.
The exact reason your immune system starts this attack is not fully understood. Researchers know that psoriasis involves two types of immune cells—T cells and dendritic cells—that become overactive, but they do not yet know what triggers that overactivity in the first place. What they do know is that psoriasis runs in families, meaning genetics play a major role, and that certain events or conditions can set it off or make it worse.
Key Takeaways
- Psoriasis is an autoimmune condition where your immune system speeds up skin cell growth, causing thick patches and scaling.
- Genetics account for a large portion of psoriasis risk—having a parent or sibling with psoriasis increases your chances significantly.
- Common triggers include stress, infections (especially strep throat), skin injuries, certain medications, and cold, dry weather.
- Alcohol use and smoking can worsen psoriasis or make it harder to treat, and weight gain may increase flare frequency.
- Not everyone with the genetic predisposition develops psoriasis, and not everyone with psoriasis has the same triggers.
Genetics: The foundation that makes psoriasis possible
If one parent has psoriasis, your risk of developing it is roughly 10 percent. If both parents have it, that risk rises to around 50 percent. However, having the genes does not may provide you will develop psoriasis—many people carry the genetic markers and never show symptoms.
Researchers have identified multiple genes involved in psoriasis, not just one. This is why the condition varies so much from person to person in terms of when it starts, how severe it is, and which parts of the body it affects. Your genetic makeup determines whether your immune system is primed to overreact, but something else has to light the fuse.
Stress as a psoriasis trigger
Stress is one of the most commonly reported triggers for psoriasis flares. When you are under stress, your body releases hormones like cortisol, which can shift how your immune system functions. For people with the genetic predisposition, this shift can activate the overproduction of skin cells.
The relationship works both ways: stress can trigger a flare, and a flare can cause stress, which then worsens the flare. Breaking this cycle often means addressing stress through whatever methods work for you—whether that is exercise, sleep, time with people you trust, or professional support. Some people find that their flares improve noticeably when they reduce stress, while others see little change.
Infections, especially strep throat
Streptococcal infections, particularly strep throat, are well-documented triggers for psoriasis flares. The connection is strong enough that doctors often ask about recent infections when someone develops psoriasis for the first time or experiences a sudden worsening.
Other infections can trigger flares too, including upper respiratory infections and other bacterial or viral illnesses. The mechanism appears to involve your immune system ramping up to fight the infection and then staying in overdrive, attacking skin cells in the process. If you notice a flare starting after you have been sick, that timing is likely not coincidental.
Skin injuries and the Koebner response
Psoriasis can appear on skin that has been injured—a phenomenon called the Koebner response. This means that cuts, scrapes, sunburns, tattoos, or even vigorous scratching can trigger psoriasis patches to form at the site of injury.
This does not happen to everyone with psoriasis, and it does not happen every time someone with psoriasis gets injured. But if you have psoriasis and notice new patches appearing after an injury, the Koebner response is likely at work. This is one reason dermatologists recommend being gentle with your skin and protecting it from unnecessary injury.
Medications that can worsen or trigger psoriasis
Certain medications are known to trigger or worsen psoriasis in some people. Beta-blockers (used for high blood pressure and heart conditions) are the most commonly cited culprit. Lithium (used for bipolar disorder) is another. Nonsteroidal anti-inflammatory drugs like ibuprofen may also trigger flares in some people, though the evidence is less consistent.
If you take any of these medications and have psoriasis, do not stop taking them without talking to your doctor. The benefit of the medication often outweighs the psoriasis risk, and your doctor may be able to adjust your dose, switch you to an alternative, or manage your psoriasis more aggressively while you continue the medication. The key is letting your doctor know about the connection.
Weather, humidity, and seasonal patterns
Many people with psoriasis notice their condition worsens in winter and improves in summer. Cold, dry air can strip moisture from your skin and trigger flares. Low humidity indoors during heating season compounds this effect. Sunlight, which many people with psoriasis find soothing, is less available in winter months.
Not everyone follows this seasonal pattern—some people flare in summer or have no clear seasonal trend at all. If you do notice your psoriasis changes with the seasons, you can plan ahead: using a humidifier in winter, moisturizing more frequently, and protecting your skin from extreme cold may help reduce flares.
Alcohol, smoking, and weight as contributing factors
Heavy alcohol use is associated with more severe psoriasis and can make the condition harder to treat. Smoking also appears to worsen psoriasis and may increase the risk of developing it in the first place. Weight gain and obesity are linked to more frequent flares and more extensive skin involvement.
These are not triggers in the same way that stress or an infection is—they are more like conditions that make your psoriasis worse overall. Reducing alcohol, quitting smoking, and maintaining a healthy weight may improve your psoriasis, though results vary. Even if these changes do not eliminate flares, they often reduce their frequency or severity.
Frequently Asked Questions
Can psoriasis be caused by poor hygiene or contagion?
No. Psoriasis is not caused by poor hygiene and is not contagious. You cannot catch it from someone else, and you cannot give it to someone else. It is an autoimmune condition rooted in genetics and triggered by internal or external factors, not by cleanliness or exposure.
Does food cause psoriasis flares?
Some people report that certain foods worsen their psoriasis, but there is no universal food trigger. Common suspects include alcohol, spicy foods, and foods high in inflammatory compounds. Keeping a flare diary to track what you eat and when flares occur can help you identify your own patterns, if any exist.
Can psoriasis develop without a family history?
Yes. While genetics are a major factor, about one-third of people with psoriasis have no family history of the condition. This suggests that genetic risk is not the only pathway to psoriasis, and that environmental triggers or other factors can activate the condition even without a strong genetic predisposition.
If I have the psoriasis gene, will I definitely develop it?
No. Many people carry genetic markers associated with psoriasis but never develop symptoms. Whether the genes are expressed depends on triggers—stress, infection, injury, or other factors. You can have the genetic risk and never experience psoriasis if those triggers do not occur.
Does psoriasis get worse over time?
Psoriasis varies widely from person to person. Some people have one flare and then long periods of clear skin. Others have chronic, ongoing symptoms. Some people's psoriasis worsens over time, while others find it improves. The course depends on your genetics, your triggers, your overall health, and the treatments you use.