However, blood glucose should be closely monitored. Hypertension Oral decongestants have the potential to elevate diastolic and systolic pressure by beta stimulation of the heart to increase cardiac rate and output and by peripheral vasoconstriction. They are contraindicated in patients with severe hypertension or severe coronary disease. Pseudoephedrine is considered to be the safest agent since its decongestant activity occurs at approximately half the dose required to significantly increase blood pressure. Tachycardia and palpitations are still frequent side effects particularly with prolonged use or if administered more often than recommended.
Phenylephrine causes hypertension as a relatively common side effect.
Phenylpropanolamine and ephedrine increase diastolic pressure and should be avoided by hypertensive patients. Prostatic Hypertrophy Oral decongestants should be used with caution in patients with prostatic hypertrophy. Sympathomimetic activity may precipitate or aggravate urinary retention. The cardiac stimulating properties of sympathomimetics can aggravate the cardiac symptoms of hyperthyroidism. Also, central nervous system stimulation causes an increased secretion of thyroid hormone which is potentially dangerous to a hyperthyroid patient.