My husband took Malaria prophylaxis prior to a deployment to South America and the Carribean several years ago. He states he received 3 or 4 doses of the medication during the 6 months and he was not allowed to donate blood for a long time (he thinks it was several years) after returning. If the medication is OK to take while nursing or pregnant and for toddlers to take (as Katherine Dettwyler suggested), does anyone know why you would not be able to donate blood? Just curious, Diane Karnbach, LLLL