Every time I go outside, I suddenly get this huge rash on my skin. It's only happened this year. The rash you describe is called photosensitivity. It can occur for some people when exposed to sunlight while taking certain medications, such as the antibiotic tetracycline used in the treatment of acne or sulpha drugs used in the treatment of diabetes or bladder infection. You could also be getting a photosensitivity allergic reaction.
Some people develop hives when exposed to cold, exercise or sunlight.
In half the cases, the skin allergy disappears after a year. The cause of this reaction is the bodies' release of histamine. If the rash doesn't respond to the drug, you should see your doctor. Also, if you have any other associated symptoms you should be seen by your doctor since there are some rare conditions with similar symptoms. We welcome your feedback.