When the weather is hot, blisters will appear on your arms. What is this? How to treat it?

This is a sweat rash. Hormone therapy can be used for a short time.

Sweat blisters are eczema changes (allergic dermatitis changes) that occur on hands or feet. At the onset, the patient's palms, soles or fingers and toes are often severely itchy, and many small, scattered or concentrated blisters can be seen, some of which are reddish papules. Some of these blisters appear quickly within a few hours, but most of them will get worse within a few days. Sometimes the collected blisters merge into large blisters, making it impossible for patients to do things with their hands or walk with their feet. These blisters are sometimes complicated with bacterial infection and purulent reaction. These acute blisters will be relieved quickly after treatment, but they will still recur. Normally, blisters will not burst, but will naturally absorb and dry up. After a week or two, the blister will peel off into a round dry dandruff wheel, and the skin will be dry, peeling and cracked, causing pain, and then it will return to normal skin. "Sweat rash" is common in young men and women and early middle age (20-40 years old). Most patients are complicated with hyperhidrosis, but this disease is not caused by the blockage or swelling of sweat ducts. It is easy to attack in summer or alternate seasons every year, lasting 3-4 weeks at a time. Some patients will become chronic diseases. Some patients have ectopic constitution or nickel allergy. Avoiding allergens can improve symptoms, but it can't be completely rooted. Some patients will get worse if they are nervous and stay up late. I don't know the real reason at present. I suggest you go to the hospital for confirmation, so that you can get better treatment.

I wish you a speedy recovery!