Published by TDP on September 20, 2017 Nasal decongestants for administration by mouth may not be as effective as preparations for local application but they do not give rise to rebound nasal congestion on withdrawal. Pseudoephedrine is available over the counter; it has few sympathomimetic effects. Systemic decongestants should be used with caution in diabetes, hypertension, hyperthyroidism, susceptibility to angle-closure glaucoma, prostatic hypertrophy, renal impairment, pregnancy, and ischaemic heart disease, and should be avoided in patients taking monoamine oxidase inhibitors.