Brief Answer:
Suspect allergic reaction

Detailed Answer:
Hello, I'm Dr. Branch, thanks for using 'Ask a Doctor'. Blisters that are confined to one area like what you describe would most likely be an allergic contact dermatitis, which is a reaction to something that touched that area, which you may or may not be aware of. Other possibilities could be an insect bite, a drug reaction, or less likely herpes.

I would continue to use the hydrocortisone, and as long as it completely heals, it wouldn't be anything you needed to worry about. If it came back, or spread to other areas, I would suggest seeing a doctor to possibly get a biopsy to confirm what the cause is.

I hope that helps, please let me know if you have any other questions about that, and I would be glad to discuss it with you further.

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Brief Answer:
Welts/blisters

Detailed Answer:
Yes, they look like fairly typical welts/blisters. It does not look like herpes, more likely an allergic contact dermatitis. I would continue to use the hydrocortisone, and it should resolve within a week.

Please let me know if you have any other questions, I'd be glad to help any way I can.

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