What Causes Blisters? 9 Possible Reasons & What to Do

Blisters can form in response to a skin irritation or inflammation, and are often a sign of allergies, miliaria or dyshidrosis. They can also emerge due to viral infections, like herpes, chickenpox or monkey pox, which can cause blisters in any area of the body. 

In some cases, the blisters may be fluid-filled. When these rupture, it can lead to spreading to other areas of the body or more significant wounds. Fluid-filled blisters can cause symptoms like intense itching, redness or pain. 

If you notice blisters and are unsure what they are related to, you should see a doctor for assessment. The doctor will evaluate other signs and symptoms as well as the characteristics and areas of the body affected to reach a diagnosis and initiate treatment. 

Imagem ilustrativa número 1

Common causes

The most common causes of blisters are: 

1. Allergic reaction

Allergic reactions can cause small blisters with white or red skin. They may contain clear fluid and may emerge with other symptoms like intense itching, crusting, and skin wounds. Blisters may form as a result of an inflammatory reaction and are prone to emerge anywhere in the body. 

Blisters from an allergy can form minutes to hours after contact with an irritating substance, like a specific food, medication, jewelry, animal fur, perfume, cleaning products, plants, latex or an insect bite..

What to do: You should cleanse the area with cold water and a mild soup and avoid further contact with the trigger. The doctor may prescribe oral or topical antihistamines and corticosteroids, depending on the severity of the reaction. Severe symptoms should be assessed in a hospital, as IV medications may be necessary. 

2. Dyshidrosis

Dyshidrosis is a skin disease that can cause small fluid-filled blisters. They generally appear on the palms of the hands, sides of the fingers or bottoms of the feet, and are associated with intense itching that can last for 3 weeks. 

The exact cause of dyshidrosis is not known, although it is more frequently noted in the summer, and during periods of stress. A family history and frequently washing your hands may also exacerbate this condition.

What to do: To relieve symptoms and prevent worsening or infections, you can apply a cold compress to the affected area for 15 minutes, 2 to 4 times per day. The dermatologist may also prescribe medications like prednisone, loratadine, and corticosteroids.

3. Monkeypox 

Monkeypox is a disease that causes itchy blisters that first emerge on the face, and then spread to the chest, hands and feet. It can also affect genital skin. 

Monkeypox is mainly transmitted from animals to people through bites of infected animals, eating undercooked food and/or coming in contact with infected animals’ body fluids. Monkeypox can also be transmitted from person to person through saliva droplets and direct contact with infected wounds.

What to do: There is no specific treatment for monkeypox, and generally patients are isolated from others until the infection resolves. Simple skin care is advised to protect the blisters and wounds from becoming infected. The doctor may prescribe analgesics to relieve other symptoms associated with this condition, as well as vaccination to prevent worsening. 

4. Chickenpox

Chickenpox is a disease caused by the Varicela-zoster virus that is associated with small blisters that form throughout the body. 

Blisters can be fluid-filled and cause symptoms like intense itching that lead to skin wounds. 

What to do: You should rest and take medications as prescribed by the doctor, like acetaminophen for fever or antihistamines to relieve itching.

You should avoid contact with other people and take measures to prevent spreading of this condition through saliva, coughing or sneezing. Chickenpox is highly contagious and is easily transmitted to those that are not immune. 

5. Miliaria 

Miliaria is characterized by the presence of small, itchy skin blisters that may contain fluid or pus. Skin burning is also common and can affect any part of the body, but is most frequent in the face, neck, back, chest and thighs.

Miliaria emerges when sweat pores become blocked, trapping the sweat under the skin and causing inflammation. This can be common in newborns, but can affect anyone at any age. Some factors that triggers miliaria include warm environments, very intense physical activity or high fevers. 

What to do: Use light, loose, cotton-based clothing to promote airflow to the skin. You should avoid using creams and ointments with mineral oils, as these can block the pores. You can apply chamomile compresses to the skin to help relieve blister discomfort. The doctor may prescribe calamine cream or other topical antihistamines. 

6. Herpes

There are two types of herpes that cause fluid-filled blisters that are associated with tingling in the area, pain, and wounds. 

Herpes simplex typically affects the lips and oral area, which is also referred to as oral herpes. This virus can also affect the genital areas, and is referred to as genital herpes. Herpes zoster, or shingles, can affect the chest, back and belly, although some blisters may also appear in the eyes or ears. 

What to do: Generally, the doctor may prescribe oral or topical antiviral medications, like aciclovir, famciclovir ou valaciclovir, to relieve pain from the blisters and prevent worsening. It is important to wash your hands after coming in contact with the blisters, and to avoid rupturing them. To prevent spreading, you should avoid kissing, avoid sharing personal objects (like utensils, cups or towels) and use a condom during all sexual contact. 

7. Pemphigus

 Is an autoimmune disease that is non-contagious and is characterized by the formation of various soft blisters on the skin. They rupture easily in hours to days and take a long time to heal. This condition can also affect areas with mucus membranes, like the mouth, eyes, nose, throat and genitals. 

What to do: Treatment should be monitored by a dermatologist, who may prescribe corticosteroids or immunosuppressants to treat or prevent blisters. Blisters and wounds that become infected can be treated with antibiotics, antifungals or antivirals. 

8. Hand, foot and mouth disease

Hand, foot and mouth disease is a highly contagious condition that is most frequently seen in children under 5. It leads to painful blisters on the hands, feet, and sometimes, with genitals. 

This disease is caused by a coxsackie group virus, and can be transmitted from person to person, or through contaminated food or objects. 

What to do: Treatment lasts for about 7 days, and is monitored by a pediatrician or family doctor. The doctor may prescribe antihistamines to relieve itching, and other medications, like acetaminophen, to relieve fever and other symptoms. 

9. Seroma

A seroma is an inflammation of the skin that leads to the formation of fluid-filled blisters. They tends to emerge around surgical incision wounds, like after plastic surgery, abdominoplasty,  liposuction, breast surgery or cesarean section surgery. 

What to do: Small seromas can be reabsorbed into the skin on their own, and resolve within 10 to 21 days. In some cases, however, the doctor may need to prescribe medications, like antibiotics, analgesic and anti-inflammatories. Larger seromas may need to be aspirated  to remove excess fluid.