A blister is a pocket of fluid that forms when layers of skin separate. Most blisters come from friction, burns, insect bites or infections. A smaller group of conditions, the autoimmune blistering diseases, happen when the body’s own immune system attacks the skin. These are uncommon, can be serious, and usually need specialist diagnosis and long-term care.
What causes blisters on the skin?
Blisters can be caused by:
- friction, burns and sunburn
- insect bites and plant reactions
- infections such as impetigo, chickenpox, shingles (kayap) and hand, foot and mouth disease (see skin infections)
- eczema and allergic contact dermatitis (see skin allergies)
- reactions to medicines
- autoimmune diseases such as bullous pemphigoid and pemphigus
- rare inherited conditions that make skin fragile from birth
Blisters that appear without an obvious cause, keep returning, or come with mouth sores deserve a medical assessment.
When are blisters a medical emergency?
Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are rare but life-threatening reactions, usually to medicines. DermNet describes them as variants of the same condition, differing in how much skin detaches: under 10% of the body surface in SJS and over 30% in TEN.
Medicines most often involved include antibiotics, some anticonvulsants, anti-inflammatory painkillers and some gout medicines. DermNet notes that SJS/TEN usually develops within the first week of antibiotic therapy, but up to 2 months after starting an anticonvulsant.
The pattern often begins with a flu-like illness, such as fever, sore throat and aching, followed days later by a painful rash that blisters and peels. Sores in the mouth, eyes and genitals are common. DermNet reports mortality of up to 10% for SJS and at least 30% for TEN, which is why early hospital care matters.
Go to the emergency department immediately if you have:
- widespread blistering or peeling skin
- painful sores in the mouth, eyes or genitals with a rash
- fever or a flu-like illness followed by a painful, spreading rash, especially after starting a new medicine
- swelling of the lips, tongue or throat, or difficulty breathing (call 999)
What is bullous pemphigoid?
Bullous pemphigoid is an autoimmune blistering disease that mainly affects older people. The British Association of Dermatologists notes that it usually affects people aged 70 and over, and it occurs in men and women equally.
Typical features include:
- severe itch, often the first symptom
- an early phase lasting weeks, with an eczema-like or hive-like rash before blisters form
- large, tense blisters filled with clear or blood-stained fluid, often on the limbs, skin folds and trunk
- crusted raw areas where blisters have burst
- mouth involvement, which is uncommon
Pemphigoid is not contagious, not caused by infection or allergy, and not hereditary. Some medicines have been linked with it, including a class of diabetes medicines (DPP-4 inhibitors) and cancer immunotherapy. According to DermNet, treatment is usually needed for several years, but in many cases pemphigoid eventually clears and treatment can be stopped.
What is pemphigus vulgaris?
Pemphigus vulgaris usually begins between the ages of 30 and 60. DermNet reports that it accounts for about 70% of pemphigus cases worldwide, and that the mouth is involved in 50 to 70% of patients.
Painful mouth ulcers that do not heal are often the first sign, so people may see a dentist or doctor for mouth problems before any skin blisters appear. The skin blisters are thin-walled and break easily, leaving painful raw areas, especially on the scalp, face, chest and back. The throat can also be affected, causing hoarseness or difficulty swallowing.
Pemphigus is a serious condition, but the American Academy of Dermatology notes that it can nearly always be brought under control with proper medical care and regular follow-up.
What other blistering diseases are there?
| Condition | Who is typically affected | Blister pattern | Mouth involved? |
|---|---|---|---|
| Bullous pemphigoid | Older adults, usually over 70 | Large, tense, very itchy blisters | Uncommon |
| Pemphigus vulgaris | Adults, usually aged 30 to 60 | Fragile blisters that break into raw areas | Often |
| Pemphigus foliaceus | Adults | Superficial, scaly, crusted patches | No |
| Mucous membrane pemphigoid | Mainly older adults | Mouth, eyes and genitals; risk of scarring | Yes |
| Dermatitis herpetiformis | Adults with gluten sensitivity (coeliac disease) | Very itchy small blisters on elbows, knees and buttocks | Rarely |
| Linear IgA disease | Children and adults | Clusters of blisters, sometimes ring-shaped | Sometimes |
| Pemphigoid gestationis | Pregnancy | Itchy blisters, often starting around the navel | Rarely |
How are blistering disorders diagnosed?
Because many conditions cause blisters, diagnosis usually combines:
- a skin biopsy from the edge of a fresh blister, to see the level at which the skin splits
- direct immunofluorescence on a second small sample of nearby skin, to show antibodies attacking the skin
- blood tests for circulating antibodies
- baseline health checks, such as blood count, kidney and liver function, blood sugar and blood pressure, before starting immune-suppressing treatment
People with eye, throat or genital involvement may also need input from other specialists.
How are autoimmune blistering diseases treated?
Treatment is individualised, depending on the diagnosis, how widespread it is, age and other health conditions. Options include:
- potent topical corticosteroids, particularly for localised pemphigoid
- oral corticosteroids to bring blistering under control
- tetracycline-class antibiotics, used for their anti-inflammatory effect
- steroid-sparing immunosuppressant medicines, to reduce long-term steroid exposure
- biologic therapy for severe or resistant disease
- skin care: gentle cleansing, non-stick dressings, and draining large blisters with a sterile needle while leaving the roof in place
Safety notes: long-term steroid tablets need monitoring of blood sugar, blood pressure and bone health. Do not stop steroid tablets suddenly. Immune-suppressing medicines increase infection risk, so report fever or spreading redness promptly.
What should people in Malaysia know about blistering disorders?
- Delayed diagnosis: early pemphigoid can look like eczema, scabies or insect bites, and early pemphigus can look like ordinary mouth ulcers. Itch or sores that persist despite treatment should be reviewed.
- Heat and humidity: sweat and friction make raw skin more uncomfortable and prone to infection. Loose cotton clothing and a cool environment help.
- Diabetes medicines: diabetes is common in Malaysia. An older person taking diabetes medicines who develops persistent itch and blisters should have their medicines reviewed, but must not stop them without their doctor’s advice.
- Traditional remedies and unregulated creams: herbal pastes, oils and powders applied to raw skin can cause irritation or infection, and some unregistered creams contain undeclared steroids.
- Fasting and medicines: if you plan to fast during Ramadan while taking steroids or immunosuppressants, discuss timing and safety with your doctor beforehand.
- Carers: many people with pemphigoid are elderly and rely on family members, who may need practical guidance on dressings and recognising infection.
Seeing Dr Kartini for blistering disorders
Blistering disorders are one of the clinical focus areas of Dr Kartini Farah Rahim, Consultant Dermatologist at Avisena Specialist Hospital, Shah Alam. Her training includes internal medicine as well as dermatology.
A consultation typically includes:
- History: when the itch or blisters began, all current and recent medicines, other health conditions, and any mouth, eye or swallowing symptoms.
- Examination: of the skin and, where relevant, the mouth, eyes and genital area.
- Tests: a skin biopsy with direct immunofluorescence, blood tests, and baseline checks before treatment.
- A management plan: medicines chosen to balance disease control with side effects, blister and wound care advice, and referral to other specialists where needed.
- Follow-up: regular reviews to monitor response and side effects and to reduce treatment gradually when it is safe to do so.
If you have widespread blistering with mouth or eye sores, or feel very unwell, go to the emergency department rather than waiting for a clinic appointment. For non-urgent assessment, see appointments.
