Side Effects Of Diphenhydramine Hcl And Phenylephrine Hcl

Side Effects of Diphenhydramine HCL and Phenylephrine HCL

Sep 2, 2010 | By Aironius French

According to RxList, diphenhydramine HCl, a first-generation antihistamine drug used to treat allergies, is an anticholinergic agent that causes extreme drowsiness. Diphenhydramine is the active ingredient in all Benadryl products, as well as in Tylenol PM and Advil PM. Phenylephrine HCl is classified as an adrenergic receptor agonist and is used most commonly as a nasal decongestant, notes Drugs.com. Phenylephrine is the main active ingredient in Robitussin and Tylenol Sinus products. Both drugs are used together in Benadryl Allergy and Sinus Headache.

Extreme Sedation From Diphenhydramine

Diphenhydramine has strong sedation effects that can lead to profound drowsiness, such that a user might fall into a deep sleep while operating machinery or driving a car. Because of its sedating effects, diphenhydramine is also used as an anti-anxiety medication, with additional common side effects such as dry mouth and throat, light sensitivity from pupil dilation, increased heart rate, confusion and hallucinations.

Asthma Attacks From Diphrenhydramine

Diphenhydramine may cause thickening of bronchial secretions that can be dangerous for patients with a history of bronchial asthma, cardiovascular disease or hypertension, according to DailyMed. In addition to precipitating bronchial asthma attacks, diphenhydramine can also cause tightness in the chest and throat, wheezing and nasal stuffiness.

Hypertension From Phenylephrine

The main side effect from phenylephrine use is hypertension; in fact, it is often used medically to induce an increase in blood pressure for some health conditions. The "PDR Guide to Drug Interactions, Side Effects, and Indications" explains that phenylephrine stimulates post-synaptic alpha receptors, which causes vasoconstriction in peripheral arteries, which in turn results in increased systolic, diastolic and pulmonary pressures. Hypertension is a known risk factor for heart attacks and strokes. Furthermore, phenylephrine can cause increased heart rate, nervousness and headaches. People with heart congestion or hypertension should not use products that contain phenylephrine.