What Causes Psoriasis and What Can Trigger Flares?

TL;DR

• Psoriasis has no single cause. It develops through immune-system activity, genetic susceptibility and environmental influences.
• A cause explains why psoriasis develops. A trigger is an event or exposure associated with its first appearance or a later flare.
• Stress is the trigger patients bring up more than any other in conversations with mama health.
• Patients often associate infections or hormonal changes with their first flare, while stress, weather and diet come up more often once they've been living with psoriasis for a while.
• Many patients can't identify one consistent trigger, which makes flares feel unpredictable — and psoriasis is also linked to a handful of other health conditions worth knowing about, even though it doesn't cause them.

What did patients identify as their main psoriasis trigger?

Stress is the trigger that comes up more than any other when patients talk to mama health about their psoriasis.

It comes up substantially more often than medication-related factors, and considerably more than weather. Patients also talk about diet, skin injury, infections, hormonal changes, disrupted routines and poor sleep.

That said, plenty of patients can't point to a specific trigger at all — for a lot of people, there just isn't a clean pattern to describe. That uncertainty is itself worth naming: patients frequently describe searching for an explanation after a flare but being unable to separate stress, weather, illness, treatment changes and everyday routines from each other.

These findings describe patient-reported associations. They don't prove that any one factor caused an individual flare.

What causes psoriasis?

Psoriasis develops through a combination of genetic susceptibility and an overactive immune response.

In psoriasis, immune cells — particularly a type called Th17 cells — release signals (including IL-17 and IL-23) that ramp up inflammation and speed up the production of skin cells dramatically: new skin cells can form and rise to the surface in a matter of days instead of the usual few weeks. That's what creates the buildup patients see and feel as thickened, scaly patches.

Genetics plays a real role, but it's not the whole story. A meaningful number of patients have a close relative with psoriasis or psoriatic arthritis, and researchers have identified specific genetic regions — including one called PSORS1 — associated with higher risk. But plenty of people develop psoriasis with no known family history, and plenty of people carry the genetic susceptibility without ever developing symptoms. Psoriasis also tends to show up at one of two points in life: in the teens to mid-twenties, or later, around the 50s to 60s.

Researchers therefore view psoriasis as an interaction between genes, immune activity and external influences — a person can carry the underlying susceptibility for years before something tips the balance into a first flare. That's exactly what a "trigger" means in the sections below.

Psoriasis is not caused by poor hygiene, personal failure or contact with another person. It is not contagious.

What is the difference between a cause and a trigger?

The cause creates susceptibility to psoriasis; a trigger may influence when symptoms appear or worsen.

This distinction is often blurred in how patients describe their own experience.

A patient might say stress "caused" their psoriasis because the first plaques appeared after bereavement or a demanding period at work. Clinically, stress didn't create the underlying genetic and immune susceptibility — it may have been one influence around the time symptoms became visible.

The same trigger can affect people differently. Cold weather may consistently precede one person's flares while having little effect on another.

Why did stress dominate patient experiences?

Patients describe stress as both a possible trigger and a consequence of psoriasis.

Across conversations about stress and flares, patients repeatedly connect flares with:

• Bereavement or grief
• Relationship breakdown
• Work pressure or job loss
• Exams and major deadlines
• Financial worries
• Traumatic life events

The recurring pattern is a feedback loop. Stress shows up before a flare, but the flare then creates more stress through itching, visible plaques, poor sleep and social anxiety. Patients across several countries describe hiding their skin, withdrawing socially, or worrying that others will view psoriasis as infectious — which can make it genuinely hard to tell whether stress started the flare or intensified after symptoms appeared.

One thing patients say they wish had come up sooner: that stress management is medically relevant here, not just a nice-to-have. Many feel their doctors treat it as secondary to the skin itself, when in practice the two are tightly connected.

Stress does not cause psoriasis by itself, but it's recognized as a possible flare trigger. Emotional support and stress-management practices may support wellbeing alongside appropriate psoriasis care.

Do triggers change during the psoriasis journey?

Patients often describe different triggers around their first flare than during ongoing psoriasis.

Infections and hormonal changes tend to show up more in first-flare stories. Patients describe psoriasis appearing after events such as:

• Streptococcal throat infections
• Viral illness, including COVID-19 in more recent onset stories
• Pregnancy
• Menopause — a recurring first-flare trigger among women in their late 40s and 50s
• A major period of stress

Once people have lived with psoriasis for longer, they more often talk about stress, cold weather, dry air, diet and skin irritation as their recurring flare pattern instead. In other words: infections and hormones tend to be part of the first-flare story, while stress, weather and diet are what patients end up managing day to day, long after that first flare.

This doesn't mean infections or hormones caused psoriasis, or that lifestyle factors determine its course — it just shows that patients' own explanations and concerns tend to shift over time. Streptococcal infection is a recognized trigger for guttate psoriasis in particular, more often in children and younger adults, and infections may precede other types of flare too.

Can medicines trigger psoriasis?

Some medicines can contribute to psoriasis appearing or worsening in susceptible people.

Recognized examples include lithium, some beta-blockers (commonly used for blood pressure), antimalarial medicines, and rapid withdrawal of systemic corticosteroids. The strength of evidence differs between medicines, and NSAIDs and certain antibiotics come up in patient conversations too, though less consistently.

Medication-related changes are the second most common trigger theme patients describe, right behind stress — symptoms appearing after starting a new medicine, changing a dose, or stopping treatment. Some patients also connect worsening symptoms with changes to strong topical corticosteroids, though these experiences don't confirm the topical medicine caused the flare. Rapid withdrawal of systemic corticosteroids is the more clearly recognized clinical concern.

A prescribed medicine should not be stopped or changed because of a suspected trigger without discussing it with the prescriber. If a treatment itself feels like it's part of the problem, our guide on psoriasis treatment options covers how to raise that with a doctor.

Can weather, alcohol or food trigger flares?

Weather and lifestyle factors may influence psoriasis for some people, but no single pattern applies to everyone.

Cold, dry winter weather is the most consistent environmental theme patients describe. Some also mention heat, sweating, humidity or sunburn.

Alcohol comes up repeatedly as something patients associate with worsening symptoms, particularly with heavier intake — enough that some patients have cut it out entirely. High-sugar foods, gluten and highly processed foods are common subjects of self-experimentation too, but no consistent "psoriasis diet" emerges from these conversations, and it's worth being honest about that rather than overstating the evidence. Our guide on psoriasis diet and food questions goes deeper into what patients and dermatologists actually say here.

Clinical guidance recognizes cold weather, heavy alcohol consumption, smoking and skin irritation as possible influences. Evidence for individual foods is less consistent. Dietary changes should not replace prescribed care, and restrictive diets may require professional nutritional guidance.

Can skin injury cause new psoriasis patches?

Psoriasis can sometimes appear where the skin has been cut, scratched, burned or otherwise injured.

This response is known as the Koebner phenomenon. Patients associate new plaques with scratches, tattoos, surgical scars, sunburn and repeated friction. The patch may appear after the injury rather than immediately, which can make the link difficult to recognize. It doesn't happen after every injury, or in every person with psoriasis. Our guide on plaque psoriasis symptoms and experiences covers this pattern in more depth alongside other plaque triggers.

Is psoriasis linked to other health conditions?

Psoriasis shares underlying inflammatory biology with several other conditions — but that's a link, not a cause.

A meaningful share of patients living with psoriasis also deal with psoriatic arthritis, and depression and anxiety come up almost as often — for many patients, managing the emotional weight of a visible, unpredictable condition is just as real as managing the skin itself. Cardiovascular disease, diabetes and osteoarthritis show up too, though less frequently.

None of these conditions are caused by psoriasis, and psoriasis doesn't cause them either. They're better understood as sharing the same underlying inflammatory processes — which is exactly why they're worth mentioning to a doctor, even if they seem unrelated to your skin. A doctor who knows the full picture is in a better position to screen for these alongside managing the psoriasis itself.

Why can identifying one trigger be difficult?

Several possible triggers may occur together, and a flare can also happen without an obvious explanation.

A person may be sleeping poorly during a stressful period, recovering from an infection, and experiencing colder weather all at the same time. Picking one event as "the cause" can oversimplify what actually happened.

A personal record can help someone reflect on patterns involving:

• Flare dates
• Illnesses or infections
• Stress and sleep
• Weather changes
• Skin injuries
• New or changed medicines
• Alcohol or dietary changes

This type of record supports reflection and appointment preparation. It can't confirm a trigger or predict future flares.

When could a flare be discussed with a healthcare professional?

Professional advice may be useful when a flare is severe, unusual, persistent or follows an infection or medication change.

A review can also consider the effect on sleep, mood, work and relationships. NICE recommends assessing psoriasis according to its physical, psychological and social impact, not only the amount of affected skin.

Questions patients could prepare include:

• Could a recent infection or medicine change be relevant?
• Could several factors be contributing at once?
• Is this flare different from my usual psoriasis?
• What information would be useful to record?
• When should the current treatment be reviewed?

Reflect on possible patterns with mama health

mama health offers a space to record day-to-day experiences and prepare questions to discuss with a healthcare professional.

Disclaimer: This content is informational. mama health offers information and support and does not replace a doctor.