What is a known adverse effect of pseudoephedrine when used for allergic rhinitis?

Pseudoephedrine, a common decongestant used to relieve nasal congestion associated with allergic rhinitis, is known to cause hypertension as a notable adverse effect. This occurs because pseudoephedrine acts as a sympathomimetic agent, stimulating alpha-adrenergic receptors, leading to vasoconstriction. This vasoconstriction can increase systemic vascular resistance, resulting in elevated blood pressure.

Studies and clinical observations have shown that patients using pseudoephedrine, particularly at higher doses or for prolonged periods, may experience increased blood pressure levels. This effect is particularly concerning for individuals with pre-existing hypertension or cardiovascular conditions, as it may exacerbate these conditions and increase the risk of hypertensive emergencies.

While other side effects such as dry mouth, nausea, and drowsiness can occur with pseudoephedrine, they are generally less significant in comparison to the impact of hypertension on overall health and safety. Therefore, it is essential for healthcare providers to monitor patients using pseudoephedrine for a history of hypertension and advise them accordingly.