With words such as AIDS, allergy and autoimmunity embedded in the popular lexicon, we often equate health with the precision and the tenor of responses to allergens and microorganisms. This leads many people to seek their own solutions to sustain, restore or even boost their immune competence, hoping to live more comfortably and longer. Here, we consider the social and clinical contexts in which these promises of enhanced immunity are pursued through popular practices known as complementary and alternative medicine and the evidence that supports these.