chelating during the first six to nine months with dmsa made me feel sicker, with ala it was ok after the first few months. you take it every 3 to 4 hours for 3 days then stop for 4 days then start again. if you dont notice any ill effects you should increase the dose up to 100mg every 4 hours. i don't what causes hives- doctors dont seem to know either, my mom gets a few every now and then and the doctors dont have a clue about the cause, (insect bites is one theory, allergies is another)