Decongestants work by narrowing blood vessels, which opens the nasal cavities and allows you to breathe. They come in both prescribed and over-the-counter doses and may be administered in pills, liquids, injections, nasal sprays and eye drops. As with most medications, there may be some side effects when taking decongestants.
Pseudoephedrine
Pseudoephedrine is an ingredient in a variety of nasal decongestants including Sudafed, Dimetapp Decongestant, Biofed, 12-Hour Cold Maximum Strength, Efidac 24 Pseudoephedrine, Cenafed, Genephed, Chlor-Trimeton Nasal Decongestant, Pediacare Decongestant Infants, Claritin-D and Contac 12-Hour. Side effects may include seizures, difficulty breathing, hallucinations, decreased heartbeat, dizziness, weakness, insomnia, restlessness, nausea and pale skin. Since this drug can be used to make methamphetamine, also known as crystal meth, an illegal drug, many drugstores have moved them behind the counter and require photo identification cards to purchase. This has led to pseudoephedrine to be removed from some over-the-counter medications.
Phenylephrine
Phenylephrine usually is used in nasal spray form. It is sold under such names as Neo-Synephrine, Vicks Sinex, Pretz-D, Rhinall, Nostril and Tur-Bi-Cal. Along with its nasal decongestion properties, phenylephrine also may be used to clear congestion from ear infections. Side effects may include insomnia, pale skin, trembling, headache, dizziness, irregular heartbeat and, possibly, an increase in congestion. This last side effect requires medical attention.
Tetrahydozoline
Tetrahydozoline is a decongestant found in eye drops. The idea is to relieve itch and redness in the eyes caused by congestion. It is sold under such names as Clear Eyes and Visine. Tetrahydozoline may cause such side effects as damage to eye blood vessels and eye redness. On rare occasions, tetrahydozoline can induce acute glaucoma.
