A recent review of central nervous system reactions to HA-blockers revealed that the incidence rate varies widely depending on the specific report, and that no single agent is more likely to induce CNS reactions than another. I A meta-analysis published in 1989 showed that CNS reactions were no more frequent with cimetidine than with placebo. Neutropenia and agranulocytosis are the most commonly encountered blood dyscrasias. Although hemolytic anemia has been reported with cimetidine, the casual role of cimetidine remains very controversial. Other factors including underlying diseases or additional drugs could contribute to these hematologic alterations.
Recovery is usually rapid after discontinuation of cimetidine.
Gynecomastia and sexual dysfunction including libido decrease and impotence have been seen during cimetidine therapy. These effects may be related to cimetidine's ability to inhibit the metabolism of estradiol. GI adverse reactions have been reported in patients receiving cimetidine. Diarrhea has been reported during cimetidine therapy but is usually mild and transient. Although rare, pancreatitis, hepatitis, jaundice, and elevated hepatic enzymes have been reported with cimetidine.