Drug Interaction Report

MONITOR: Antihistamines may suppress the patient's response to histamine phosphate. The length of suppression varies and is dependent on the patient, type of antihistamine, and the duration of antihistamine therapy. The duration of suppression may range from 24 hours with chlorpheniramine or up to several weeks with second-generation antihistamines.

MANAGEMENT: Clinicians should be aware of the potential for falsely insignificant or false-negative results when administering histamine phosphate to patients treated with antihistamines.

GENERALLY AVOID: Alcohol may potentiate some of the pharmacologic effects of CNS-active agents. Use in combination may result in additive central nervous system depression and/or impairment of judgment, thinking, and psychomotor skills.

MANAGEMENT: Patients receiving CNS-active agents should be warned of this interaction and advised to avoid or limit consumption of alcohol. Ambulatory patients should be counseled to avoid hazardous activities requiring complete mental alertness and motor coordination until they know how these agents affect them, and to notify their physician if they experience excessive or prolonged CNS effects that interfere with their normal activities.