Just asked husband about it as he knows better than me. (Obviously)
Husband's only knows he is allergic to penicillin and apparently chalk. He's a climber and after several years off took it up again. He immediately got horrendous rashes on his hands. Took him forever to work out it was the chalk that was giving him hives. At school he used to get nose bleeds and unexplained rashes on his hands during term time that would clear up during holidays. Suddenly it made sense years later!
He then started getting problems with two pairs of his puma trainers. He only gets it on the bottoms of his feet and between his toes not the tops. It got so bad, his feet looked like they were falling apart. Again, took a while to realise it was the shoes doing it.
He is definitely fine with latex though!
He tried everything to try and get rid of the rashes as they would stay for weeks. E45, steroid creams, various moisturisers. Nothing worked. In the end he tried a cream called 'Cream On!' from climbing store. The stuff is AMAZING - cleared up his rashes v quickly.
I also swear by the stuff. I'm very fair skinned but unfortunately even sensitive skin suncreams don't really agree with me at all. I do use it creme, but try and avoid the sun instead if I can - sometimes I get caught out though. I can't use moisturisers or after sun at all. This stuff not only makes the burn go within a couple of days, but it stopped me peeling and doesn't give me the burning sensation I get from sun creams and moisturisers.
Its not easy to get hold of (climbing stores seem to be only places we can find) and its not that cheap (about £10 a tube) but it does work, very quickly when nothing else seems to. Its all natural ingredients (mainly essential oils), no manufactured chemicals. They do a creme which is better for rashes and the rub on bar which works well on sunburn. They do one in a little tin which is great for handbag. It smells a bit funny, but its great. Worth every penny imo.