Decongestants work by causing blood vessels to constrict. This helps relieve congestion caused by the dilation of blood vessels in the nasal passages. Phenylephrine and phenylpropanolamine are two common forms of these drugs. These over-the-counter drugs can bring temporary relief from congestion.

How long do decongestant tablets take to work?

Pseudoephedrine starts to work in 15 to 30 minutes, but you should feel a lot better after 30 to 60 minutes. How long can I take it for? Pseudoephedrine can be taken for a few days, usually up to 5 to 7 days, for the short-term relief of a stuffy or blocked nose.

Are decongestants bad for you?

Taking a decongestant can temporarily ease congestion, but it can also create a slight increase in your blood pressure. If you already have high blood pressure, especially if it's not controlled, this may be a concern. Decongestants also can interfere with the effectiveness of certain blood pressure medications.