What could painful quarter size blisters on the arms be?

Painful quarter-size blisters on the arms could be a symptom of several different conditions. Here are a few possible causes:

1. Shingles (Herpes Zoster): Shingles is a viral infection caused by the varicella-zoster virus, which is the same virus that causes chickenpox. It typically presents with a painful, blistering rash on one side of the body, often on the arms or torso.

2. Cellulitis: Cellulitis is a bacterial infection of the deeper layers of the skin. It can cause fever, chills, and pain, along with redness, swelling, and blistering of the affected area.

3. Impetigo: Impetigo is a contagious skin infection caused by bacteria, such as Staphylococcus aureus or Streptococcus pyogenes. It typically starts as small blisters that quickly rupture, leaving a honey-colored crust.

4. Allergic Reactions: Some people may develop an allergic reaction to certain substances, such as plants, foods, or medications, which can manifest as painful blisters on the skin.

5. Autoimmune Disorders: Certain autoimmune disorders, such as pemphigus vulgaris, can cause blisters to form on the skin. These blisters are typically fragile and can easily rupture.

6. Contact Dermatitis: Contact dermatitis is a skin reaction that occurs when the skin comes into contact with a substance that it's allergic or sensitive to. This can cause blisters, redness, and itching.

7. Burns: Severe sunburn or other types of burns can cause blistering of the skin.

If you're experiencing painful quarter-size blisters on your arms, it's important to see a doctor to get an accurate diagnosis and appropriate treatment. The doctor may recommend further tests, such as a skin biopsy or culture, to determine the exact cause of the blisters. Self-treatment is not advisable as some conditions may require specific medications or medical intervention.