Decongestants such as pseudoephedrine (sold as Sudafed and other brands), phenylephrine (sold as NeoSynephrine and other brands and oxymetazoline (sold as Afrin and other brands), work by constricting blood vessels. By making the blood vessels smaller they reduce swelling. When taken by mouth, pseudoephedrine will cause blood vessel constriction throughout the body, with the vessels in the nose shrinking more than others. Nose sprays that contain phenylephrine or oxymetazoline work primarily on the blood vessel in the nose, but some of the drug is absorbed, so there is a theoretical risk of blood vessels in other parts of the body constricting as well.
The constricting of blood vessels can theoretically be a problem for people with heart disease and with high blood pressure. (For example, they could make heart failure worse and increase blood pressure). Although there is a theoretical risk, I cannot find any evidence that a real risk exists. Several studies have looked at the effects of usual dose pseudoephredrine in people with high blood pressure. When used as directed, psudoephedrine does not have any effect on blood pressure. There does not appear to be a problem with pseudoephedrine, phenylephrine or oxymetazoline when used as directed by people with high blood pressure or heart disease.
I usually advise people to use a nasal spray or drops. You are putting the drug where it is needed and can reduce the amount of drug getting into the system. Simple nose sprays that contain saline (such as Ocean Nasal Spray) can be very useful for people with a stuffy nose. For people with a runny nose, a nose spray that contains either phenylephrine (.025 %) or oxymetazoline is my usual recommendation. Nose sprays should only be used for a couple of days. If used for longer periods of time, you may develop a condition called rebound nasal congestion. The nasal stuffy comes back because of the absence of the nasal spray effect. I do not usually recommend pseudoephedrine for people with heart disease or high blood pressure. Several years ago, another decongestant taken by mouth called phenylpropanolamine, was removed from the market. Scientists at Yale University found that women who took this decongestant increased their risk of having a stroke. Although no such risk appears to exist with pseudoephedrine, I usually only recommend it when nose sprays do not work.
