A blister is a small pocket of fluid that forms in the upper layers of skin.

On injury of your skin, the damaged upper layer of skin (epidermis) tears away from the layers beneath and fluid (serum) collects in the space to create a blister.

Blisters prevent the area from becoming further damaged by protecting the skin and giving it time to heal.

Blister causes include:

  • Repeated rubbing, friction or pressure
  • When skin is exposed to excessive heat – for example, after sunburn
  • When your skin comes into contact with substances such as cosmetics, detergents and solvents
  • Various medical conditions including chickenpox, scabies, foot and mouth disease, eczema and cold sores.
  • Blood blisters occur when skin is pinched or bruised. The blister bubble is red or purple, as if blood is pooling in the blister.
  • Medication: Reactions to medications vary. In some cases, there is only an increased sensitivity to the sun, which can lead to blistering sunburn if the skin is exposed to the sun.

How is it diagnosed?

If the cause of your blisters is not obvious, your doctor will ask about your family history and your personal medical history, including any allergies you have and any medications you take, including over-the-counter medications.

You will also be asked about any recent exposure to irritating chemicals or allergens.

If your doctor suspects an allergic reaction, he or she may recommend patch tests with chemicals to identify the allergen. Some blistering diseases are diagnosed with a skin biopsy, in which a small piece of tissue is removed and examined in a laboratory.

What are your treatment options?

Most blisters heal naturally and don't require medical treatment. As new skin grows underneath the blister, your body slowly reabsorbs the fluid in the blister and the skin on top will dry and peel off.

Consult with your doctor if:

  • You think your blister is infected (it will fill with pus)
  • It is very painful
  • It keeps coming back
  • It is in an unusual place, such as on your eyelids or inside your mouth
  • It is caused by severe sunburn, burns or scalds or an allergic reaction

Antibiotics may be prescribed to treat an infected blister.

To eradicate liquid, try not to pierce a friction blister with a needle as it may become infected. Cover it with a soft dressing or plaster if it hurts and allow it to heal on its own.

If its breaks, wash the area with soap and water, then apply a bandage. If a blister is very large or painful, your doctor may drain it and apply an antibacterial cream to prevent infection.

There are different ways to treat blood blisters and burst blisters. Consult with your doctor or Clicks pharmacist.

Can it be prevented?

There are a number of things you can do to avoid getting blisters caused by friction, sunburn or chemicals. For example, you can:

  • Wear comfortable, well-fitting shoes
  • Keep your feet dry with thicker socks or talcum powder
  • To protect your hands, wear gloves when handling chemicals
  • Use sunscreen
  • Wear protective gloves when using tools such as shovels or pickaxes, and when doing manual work like gardening
  • As much as possible, avoid irritants and allergens that tend to trigger eczema
  • To prevent chickenpox and to help prevent shingles later, have your child immunised with the varicella vaccine.

What to do now

Baby immunisations are available at Clicks clinics, including for chickenpox. Stay on track with your little one's immunisations with the Clicks childhood vaccination schedule. 

To make an appointment at a Clicks Clinic, call 0860 254 257 or visit Clicks Clinics online.

The accuracy of this information was checked and approved by physician Dr Thomas Blake in December 2015