Does anyone know what this might be?

[AngryGinger]

Slightly red, I think due to being in the sun. Isn’t sensitive and doesnt hurt. But feels slightly warm and drier than the rest of my arm to the touch. Have had factor 30 on my arms and wasn’t outside between 11.30 and 1pm. I haven’t used any body care that I wouldn’t usually, in fact just shower gel today. Any ideas?

And only on one arm!

Heat rash? Taking anti histamines would help e.g. Piriton.

Heat rash. Sun cream doesn't prevent heat rash.

I feel like heat rash is something I should know about as an adult haha! Will take a piriton now. I have no idea how to stop it happening again though, as I was wearing a plain t shirt with nothing covering etc

Heat rash or sun allergy. Piriton should help.

Was it a new sun cream? Could be a reaction to that.

It may be a one-off. If it happens again, then in future take a once-a-day antihistamine every sunny morning to prevent it.

Some perfumes can react with strong sunlight on your skin?

If you're in the UK I think our mini heatwave is coming to an end next week so a small silver lining there for you.