Indicated for: allergic rhinitis; urticaria
Route of administration: oral
Substance: diphenhydramine (antihistamine)
ATC: R06AA02 (Respiratory system | Antihistamines for systemic use | Aminoalkyl ethers)
Diphenhydramine is a first-generation antihistamine used to treat allergies, insomnia, motion sickness, and cold symptoms. It works by blocking H1 histamine receptors, thereby reducing allergic symptoms such as sneezing, itching, runny nose, and hives.
In addition to its antiallergic effects, diphenhydramine has sedative properties and is commonly used as a sleep aid for short-term insomnia. It is also effective in preventing and treating nausea and vomiting associated with motion sickness.
Diphenhydramine is available in tablet, capsule, syrup, or injectable forms. It is used in both adults and children but should be administered with caution, as it can cause significant drowsiness and impair concentration.
Common side effects include drowsiness, dizziness, dry mouth, constipation, and difficulty urinating. In rare cases, more severe reactions such as confusion, hallucinations, or severe allergic reactions may occur. Patients should avoid alcohol or other sedatives while taking diphenhydramine.
Patients should strictly follow the doctor’s or package instructions regarding dosage. Diphenhydramine is not recommended for long-term use and should be avoided in individuals with glaucoma, prostate enlargement, or other conditions that may be worsened by its anticholinergic effects.