Itchy arms, back, legs, and stomach

For about 4 days now, my arms, legs, back, hands, and stomach have been itchy, mainly at night, but intermittently throughout the day. I am wondering what this could be. I have been taking Banadryl and I have been putting Aquaphore lotion on the places it itches. One of these is helping, but not sure which one, since I do them both at the same time. The benadryl also helps me sleep. Before this started, and continuing still, I have been really thirsty lately and very tired at school. I am almost fifteen years old, and a male. I am just wondering what this itching could be. I don't want to have to take benadryl for the rest of my life. If this is an allergic reaction to something, couldn't turn into a severe allergic reaction, causing death? I am very scared about this. I am also itching like crazy!!!!!! Please help!

[Dr Rajput]

Hi, your history is suggestive of allergic dermatitis. This can be induced by environmental stimuli, such as heat, cold, pressure applied to the skin, exercise, water, vibration, and sunlight. Hence it is very important to rule out any of these exposures recently before the trigger of itching. The triggering factor should be identified and further exposure should be avoided.
This condition can be diagnosed with proper history and allergen challenge test by skin specialist or immunologist. Allergic reaction of yours seems to be mild type. Hence, it is usually not life threatening. No need to worry. Rarely allergic reaction can be severe type i.e. type I reaction (anaphylactic shock).

Initial treatment includes start of second generation anti histamines. Even H2 antihistamines can be considered. Adding steroids can be quite helpful to alleviate the inflammation and reduce itching. Desensitization methods can be employed if particular agent is identified.
I suggest you to consult skin specialist/immunologist for detailed evaluation. Take care and regards.