i have been a sufferer of PH for about 4 yrs and have now just come back from hols without it !
I used to get it all up my arms , around my waist and bottom of legs.
After scouring the net for ages due to the fact PH is sooooooooo irritating i found a couple articles that i went for and they were a success. My main problem was sweatglands blocking up.
1) Biz Buin ALLERGY suncream (apply 20 mins before going out into sun.
2) When sunbathing keep a small towel nearby to wipe away sweat straight away from areas that you know will kick it off.
3) I done 15 mins in sun then under parasol for 30 then back for 15 mins again in sun and so on.
4) apply suncream again about 3 hrs later when in shade after wiping away any sweat and stay shaded for 20 mins.
5) There was a pool shower that i used also to keep cool.
6) the last 3 days i pushed my luck and spent an hour each time in the sun and i think that because my skin was looked after (as above) it stopped it from occurring.
Its sounds a lot but its not really that much hassle ,i ended up with a very good colour and holiday was soooooooooo much more enjoyable.
Hope this helps anyone