beach sand irritation

My son's penis becomes red and irritated every time we swim and play at the beach. I have tried using cotton underwear, cutting the netting out of the bathing suit and don't know what else to do for him. We love the beach but he hesitates to swim and play due to this.

[Dr_Aparna]

Hi,
Physical allergies are allergic reactions to cold, sunlight, heat, or minor injury.Water contact can cause aquagenic urticaria, presumably due to chlorine or some other trace chemical in the water, although distilled water has been known to cause this reaction.
He could be reacting to the beach water if it is polluted wiyh some kind of chemicals or it could be the water's temperature.
It could also be due to the abrading quality of the sand particles.Just apply a soothing oil like eucalyptus or calamine lotion. If it is associated with itching you can give him Benadryl.There is really no cure for it.
ref:http://www.myonlinewellness.com/topic/physicallergy