Pompholyx, also called dyshidrotic eczema, is caused by an inflammatory response in the skin of the hands and feet, not by a single identifiable trigger. Despite its older name (“dyshidrosis,” coined in 1873), the condition has nothing to do with sweat gland malfunction. The underlying process is spongiosis: fluid accumulates between skin cells in the thick epidermis of the palms, soles, and finger sides, producing the small, tense, intensely itchy blisters the condition is known for. What drives that fluid buildup varies from person to person, but research points to a consistent set of triggers.
Allergic Contact With Everyday Products
Contact allergy is the single largest identified cause. In a three-year study of 120 pompholyx patients, allergic contact accounted for 67.5% of cases. The most common culprits were cosmetic and hygiene products (31.7%), followed by metals (16.7%). Nickel is widely considered the dominant metal allergen, with cobalt and chromates close behind. Other confirmed triggers include hair dye ingredients, rubber accelerators in gloves, and formaldehyde-based preservatives found in cleaning products and personal care items.
What makes pompholyx tricky is that the allergic reaction doesn’t always happen where the allergen touches the skin. You might handle a nickel-plated object and develop blisters hours or days later on the sides of your fingers or the soles of your feet, far from the original contact point.
Metals in Food
Metal sensitivity can also be triggered from the inside. People who are sensitive to nickel or cobalt may experience flares after eating foods high in those metals. This can happen even when standard patch testing comes back negative. High-nickel foods include chocolate, oats, nuts, and canned goods. Cobalt is concentrated in leafy greens, liver, and certain shellfish. Researchers have developed point-based elimination diets that reduce dietary cobalt and nickel intake, and some patients see a meaningful drop in flare frequency after following them for several weeks.
The Atopic Connection
About 50% of people with pompholyx also have atopic dermatitis or a family history of atopic conditions like asthma, hay fever, or allergic sinusitis. This genetic predisposition toward overactive immune responses makes the skin more reactive to triggers that wouldn’t bother someone without the atopic trait. If you’ve had eczema elsewhere on your body, or if allergies run in your family, your risk of developing pompholyx is substantially higher.
Fungal Infections Elsewhere on the Body
One of the more surprising causes is a distant fungal infection, most commonly athlete’s foot. When your immune system mounts a response against a fungal infection on your feet, it can produce what’s called an “id reaction,” a generalized inflammatory response that shows up as pompholyx-like blisters on the hands. The blisters contain no fungus; they’re a byproduct of the immune system’s overreaction. Treating the underlying fungal infection often resolves the hand blisters entirely, which is why persistent or unexplained pompholyx sometimes warrants checking for tinea pedis.
Stress as a Trigger
Stress does not cause pompholyx on its own. But if you already have the condition, stress is one of the most commonly reported triggers for a new round of blisters. Many patients describe a pattern where blisters appear during periods of high emotional stress and keep appearing until the stress eases. The American Academy of Dermatology draws a clear distinction: stress triggers flares in people who are already susceptible, but it cannot create the condition from scratch.
Heat, Humidity, and Sweating
Warm weather and sweating are closely linked to pompholyx flares, though the relationship is indirect. Sweating doesn’t cause the blisters (again, the sweat glands themselves are normal), but moisture trapped against the skin appears to aggravate the inflammatory process. Higher temperatures have been associated with poorly controlled eczema in studies adjusting for other variables. Warm seasons also increase pollen production, which can compound the problem for people with atopic tendencies. Rubber or plastic footwear that traps moisture is a well-known aggravator, and eczema organizations specifically recommend avoiding shoes that promote sweating.
Occupational Exposure
Certain jobs carry a higher risk because of repeated contact with water, chemicals, or irritants. Healthcare workers face the highest rates of hand eczema onset, with 17.9% of affected individuals in one large cohort reporting that their symptoms first appeared while working in healthcare. Nursing professionals, personal care workers, housekeepers, cleaners, and shop workers all show elevated rates. The common thread is “wet work,” meaning frequent hand washing, prolonged glove use, and direct contact with fluids. Each of these strips the skin’s protective barrier and makes it easier for irritants and allergens to penetrate.
Hairdressers, florists, and metalworkers also face elevated risk due to regular contact with dyes, plant allergens, and industrial metals, respectively. If your pompholyx appeared after starting a new job or changing your work routine, the occupational connection is worth investigating.
Multiple Triggers Acting Together
For most people, pompholyx isn’t caused by a single factor. A genetically atopic person working in healthcare might tolerate mild nickel exposure for years, then develop their first flare during a stressful period in warm weather. The combination of a predisposed immune system, barrier damage from frequent hand washing, a contact allergen, and an environmental trigger can collectively push the skin past its threshold. This layered nature is part of why pompholyx can seem unpredictable. Identifying and reducing even one or two triggers often makes flares less frequent and less severe, even when you can’t eliminate every contributing factor.