Antihistamines are used as treatment for symptoms of allergies such as runny nose. Dr. Daniel Jackson and Dr. Janet Fraiser both took them to deal with allergies and they were also used to starve the body of histamine to fight off the virus that was brought back from the Land of Dark. (SG1: "The Broca Divide") Dr. Meredith Rodney McKay, the Chief Science Officer of the Atlantis expedition and a member of the First Atlantis Reconnaissance Team is known to take them, although it is hinted that they are unnecessary and a sop to his hypochondria. (SGA: "Missing")