Most people who have allergies are familiar with nasal congestion. This can include a stuffy nose, clogged sinuses, and mounting pressure in the head. Nasal congestion is not only uncomfortable. It can also affect sleep, productivity, and quality of life.

Antihistamines may help prevent allergy symptoms. But sometimes you may need to take additional medications. This is especially the case if you need to relieve sinus pressure and a congested nose. Decongestants are over-the-counter medications that help break this cycle of congestion and pressure.

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. However, they don’t treat the underlying cause of allergies. They merely offer relief from one of the more problematic symptoms of common inhalant allergies.

Decongestants are relatively inexpensive and readily available. Still, they’re more difficult to obtain than over-the-counter antihistamines.


Pseudoephedrine (e.g., Sudafed) is another class of decongestants. It’s offered in limited forms in certain states. It may be available through the pharmacist, but other states might require a prescription. This ensures proper and legal use, and prevents drug interactions. Pseudoephedrine is a raw material used in the illegal manufacture of the dangerous street drug crystal methamphetamine.

Congress passed the Combat Methamphetamine Epidemic Act of 2005 to limit the damage to communities caused by abuse of this drug. President George W. Bush signed it into law in 2006. The law strictly regulates the sale of pseudoephedrine, pseudoephedrine-containing products, and phenylpropanolamine. Many states have also enacted sales restrictions. Typically, you have to see a pharmacist and show your ID. Quantities are also limited per visit.

Decongestants are stimulants. Potential side effects include:

  • anxiety
  • insomnia
  • restlessness
  • dizziness
  • high blood pressure, or hypertension

In rare cases, pseudoephedrine use may be linked to an abnormally rapid pulse, or palpitations, also called an irregular heartbeat. Most people do not experience side effects when they use decongestants correctly.

You will need to avoid these medications or take them under close supervision if you have the following:

  • type 2 diabetes
  • hypertension
  • overactive thyroid gland, or hyperthyroidism
  • closed angle glaucoma
  • heart disease
  • prostate disease

Pregnant women should avoid pseudoephedrine.

Decongestants are often taken once every 4-6 hours, ideally for no more than one week at a time. Other forms are considered controlled-release. This means they are taken once every 12 hours, or once a day.

People who are taking any drug from a class known as monoamine oxidase inhibitors (MAOIs) should not take decongestants. Certain other drugs, such as the antibiotic linezolid (Zyvox), may also cause a serious drug interaction.

Consult with your doctor before taking a decongestant if you’re currently taking any other medications. You shouldn’t take more than one decongestant at a time. Although they might have separate active ingredients, you may still put yourself at risk for an interaction.

Most people take decongestants in a pill form. Nasal sprays feature a decongestant that is delivered directly into the nasal cavities. The American Academy of Family Physicians (AAFP) recommends that you don’t use spray decongestants for longer than three days at a time. Your body may grow dependent on them, and then the products will no longer be effective in alleviating congestion.

Nasal spray decongestants may provide temporary relief from congestion. However, they’re especially prone to inducing tolerance for the drug. This tolerance may result in “rebound” congestion that leaves the user feeling worse than before treatment. Examples of these nasal sprays include:

  • oxymetazoline (Afrin)
  • phenylephrine (Neo-synephrine)
  • pseudoephedrine (Sudafed)

Studies have shown that the combination of an antihistamine drug and a decongestant is better at relieving the symptoms of allergic rhinitis due to seasonal inhalant allergies. These drugs only offer symptomatic relief and should be used with some caution. But they can be important weapons in the ongoing battle against the misery of allergies.

Sometimes taking decongestants aren’t enough to alleviate severe nasal allergy symptoms. If you’re still having bothersome symptoms despite taking medications, it may be time to see a doctor. The AAFP recommends seeing a doctor if your symptoms don’t improve after two weeks. You should also call a doctor if you develop a fever or severe sinus pain. This could indicate sinusitis or a more severe condition.

An allergist can help you determine the exact causes of your congestion and recommend methods of more long-term relief. Prescription decongestants may be necessary for the most severe cases.