What exactly do you mean by sun poisoning - sunburn or photodermatitis? Anyone can get sunburnt - it is basically skin damage due to an excessive exposure to sunlight. Photodermatitis however is simply an unusual sensitivity to sunlight - symptoms similar to sunburn may be experienced with even minimal exposure to sunlight. For mild sunburn, you basically need to keep yourself well hydrated, both by drinking lots of water and applying water or other moisturizing substances to the skin. You should not use a moisturizing lotion or cream, as the skin is sensitive and blistering, but aloe gel or vitamin E oil is quite safe and effective. If you take these steps and also avoid exposure to the sun, your skin will heal within a week or two. Severe sunburn however takes longer and requires medical attention.
If you have photodermatitis, you need to determine the cause of the condition before being able to treat it - it could be that you have developed an allergy or some disorder of the immune system, or it may be a reaction to some medication or a skin product that you have been using. You can treat the rash that appears in the same way as you would treat sunburn, but to permanently solve the problem you will need to visit a doctor.
answered by M W