Strip your child down
loose cotton clothing
cool baths
I would use bepanthen or Aloe Vera gel

I would also suggest cool baths and loose fitting clothing, and perhaps just a nappy on if you are at home.

Bath your baby in cool water on a few occasions, not just once. You can put aluminium free talcum powder on it. I don’t know whether or not it is still recommended. If nobdy comes up with any suggestions, perhaps ask a baby nurse or a pharmacist for suggestions.