Nasal Decongestants Overview and Side Effects

Nasal decongestants are used to treat congestion (stuffy nose, runny nose, etc...). Congestion is usually caused by the common cold, and upper respiratory infection or allergies. To understand how nasal decongestants work it is important to explain how congestion occurs.

Many people think that congestion is caused when mucous (also called phlegm or nasal drainage) blocks the nasal passageways. This is only partially true. Congestion occurs when the blood vessels lining the nose become enlarged. Most nasal decongestants, therefore, cause vasoconstriction (cause the blood vessels to shrink).

There are also some nasal decongestants that work by blocking a chemical in the body called histamine. These are more commonly used as oral medications than as nasal sprays. Examples of antihistamines include Zyrtec (ceterizine), Claritin (loratadine), Allegra (fexofenadine), and Benadryl (diphenhydramine). Histamine is a molecule that causes the blood vessels to become larger, inflammation, itching and many of the symptoms that occur during an allergic reaction. Antihistamine nasal decongestants block histamine and work very well for people suffering from seasonal allergies.

Man using nasal spray
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Types of Decongestants

Many decongestants are combination medications marketed as cold remedies that may contain an antihistamine along with another type of decongestant. For example, Dimetapp, Claritin-D, or Chlor-Trimetron. Combination medication often aims to reduce one side effect with a medication that has the opposite effect. For example, a medication that uses a decongestant such as pseudoephedrine which can cause jitteriness and insomnia may be paired with an antihistamine like Benadryl (diphenhydramine) that can cause sleepiness.

Other examples of nasal decongestants include:

  • oxymetazoline (Afrin)
  • pseudoephedrine (Sudafed)
  • phenylephrine
  • levo-methamphetamine
  • naphazoline
  • phenylpropanolamine (as of December 2015 the FDA is taking steps to remove this medication from the market)
  • propylhexedrine (Benzedrex, Obesin)
  • synephrine (Neo-synephrine, bitter orange extract)
  • tetrahydrozoline (imidazoline)
  • mometasone furoate monohydrate (Nasonex)
  • fluticasone (Flonase)
  • budesonide (Rhinocort)
  • ciclesonide (Omnaris)

Nasal sprays are often preferred over oral medication because they provide fairly immediate relief of nasal congestion and may have fewer side effects since the medication is localized to a specific area of the body.

Side Effects and Contraindications

Though many nasal decongestants are available over-the-counter you should always check with your healthcare provider or pharmacist before using a nasal decongestant.

Many nasal decongestants are contraindicated for patients who have glaucoma, heart problems or high blood pressure since they can increase your heart rate and blood pressure. For this reason, you may need to be cautious about your caffeine intake while using nasal decongestants. Men who have an enlarged prostate may have difficulty urinating when taking decongestants. Many nasal decongestants should not be taken by individuals who are also taking MAO inhibitors. You also should consult your practitioner before using nasal decongestants if you are pregnant or breastfeeding. Always follow the directions on the label carefully and consult your healthcare provider or pharmacist with any questions you have before using a nasal decongestant.

3 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Naclerio RM, Bachert C, Baraniuk JN. Pathophysiology of nasal congestion. Int J Gen Med. 2010;3:47-57. doi:10.2147/ijgm.s8088

  2. American Academy of Otolaryngology - Head and Neck Surgery. Antihistamines, decongestants, and cold remedies.

  3. Medscape. Safe use of nasal decongestants.

Additional Reading
  • Merriam Webster. Histamine.

By Kristin Hayes, RN
Kristin Hayes, RN, is a registered nurse specializing in ear, nose, and throat disorders for both adults and children.