Uses, Benefits and Side Effects of Decongestants.

Decongestants Overview

Decongestants are an effective treatment option for people with seasonal allergies.  Allergies often involve a severe stuffing of nose, making it extremely difficult to breathe through your nose. Generally, antihistamines are used to treat this condition; however, where antihistamines do not work, decongestants are an efficient treatment option to prevent and treat stuffing of nose.

Man with Seasonal Allergies

How Do Decongestants Work?

Allergies usually stimulate the nose to produce extra mucus and cause swelling of nasal tissues, leading to the stuffing of the nose. This stuffing of nose results in a reduction in the passage of air to pass through the nose, leading to shortness of breath and difficulty in breathing. Decongestants provide ease in this condition by constricting the blood vessels within the area, thus reducing nasal blood supply to the sinusoids. This vasoconstriction helps shrink the swollen blood vessels and tissues, therefore, providing relief.

Types of Decongestants

Decongestants are available in different forms, including nasal sprays, liquids, nose drops, ointments, and pills. The doctors prescribe the most suitable form for the patient after a thorough examination. Their effectiveness varies due to a number of factors, including their composition, intensity, and side effects.

  • Nasal types act for a shorter time, usually 3-4 hours. However, nasal treatments with a higher intensity can also last for 8 to 12 hours. Nasal decongestants also pose a higher risk of rebound congestion. 
  • Oral types, in the form of pills, are less effective as compared to other forms and take longer to work. However, they also tend to have lesser side effects, such as rebound congestion. 
  • Topical types are more effective than oral, showing a more rapid action. They also have minimal side effects.
Pills and Capsules of Decongestants

Decongestants containing substances ephedrine, phenylephrine, propylhexedrine, naphazoline, and levmethamphetamines usually compose short term decongestants, acting for 3-4 hours. On the other hand, treatment containing oxymetazoline and xylometazoline can work over a prolonged period of 8-10 hours.


Decongestants are beneficial because they provide a quick and effective action, and can be medically used in situations where antihistamines are rendered ineffective. They offer temporary but rapid and effective relief from a stuffed nose, caused by a number of reasons including:

  • sinusitis
  • rhinitis
  • common cold
  • hay fever
  • allergic conjunctivitis
  • other seasonal allergies
  • chronic allergic reactions
  • stuffy nose due to cold
  • inflammation of the nose due to allergies

The treatment varies from person to person and is also dependent upon the intensity of allergic reactions. Mild allergic reactions can usually be easily treated through anti-allergic medicines and seldom require decongestants. A moderate allergic reaction, however, usually requires this treatment. In case of a severe allergic reaction, the doctor might prescribe a decongestant along with an antihistamine for more effective results. However, the doctor can only assess the intensity of allergic reactions after a checkup. 

Side Effects

While decongestants are useful to treat stuffy nose, it might still show several side effects, including:

  • anxiety
  • insomnia
  • rebound congestion
  • dizziness
  • high blood pressure
  • restlessness
  • headache
  • tremors
  • loss of appetite
  • urinary retention

Some people may experience side effects similar to that of an irritant, including:

  • burning
  • dryness
  • local irritation
  • sneezing
  • stinging

Conditions such as heart diseases, type 2 diabetes, overactive thyroid gland, hypertension, prostate diseases, pregnancy, and glaucoma increase the risk of side effects due to decongestant use. Similarly, children under the age of 6 should be avoided being given decongestants. Therefore, decongestants should be strictly used only after a thorough medical examination and upon the doctor’s recommendation. Furthermore, any medical condition experienced by the patient and any medications being currently taken by the patient must be disclosed to the doctor, to allow him to assess the situation to a higher degree of accuracy. 

Nasal Injection of Decongestants

Precautions of Decongestants

  • Substances such as pseudoephedrine are sometimes linked to an abnormally rapid pulse or palpitations. Therefore, they should be used only upon the recommendation of a doctor.
  • People with medical conditions such as overactive thyroid gland, hypertension, prostate diseases, pregnancy, and heart diseases should avoid using pseudoephedrine.
  • Decongestants should not be taken for more than 3-5 days. Using decongestants over a long period has shown significant health issues, including a more severe stuffing of nose (rebound congestion) when you stop taking decongestants. In some cases, prolonged use can also develop rhinitis medicamentosa, a form of rhinitis that can be challenging to treat effectively.
  • Certain drugs such as linezolid and monoamine oxidase inhibitors have a greater tendency to react with decongestants and cause a severe reaction. Therefore, people using these drugs should avoid using a decongestant.
  • It is advised to drink more amounts of fluids, especially water, when taking a decongestant and other medications for seasonal allergies.
  • The preferred mode of administration also varies in each patient. Some patients might have to be administered the decongestant in a systematic way. Therefore, they should only be used with prior approval and under the supervision of a doctor.


Decongestants are useful for an extensive number of diseases, including sinusitis, rhinitis, chronic allergic reactions, hay fever, cold, and other seasonal allergies. However, due to the possible side effects of a decongestant, they should be used only if recommended by a doctor. Furthermore, they should not be administered unsupervised or for a prolonged period. Overdosage or prolonged use might result in side effects, including rebound congestion, restlessness, dizziness, headache, and high blood pressure. The patients should also inform the doctor about any medical condition that they suffer from, or any medication they are using to avoid any adverse reaction of a decongestant.

Written by: Madiha Ather Hashmi (June 25, 2020)

Medically Reviewed By
Dr. Ahmed Abdelmajeed
Alexandria University Hospital

I have reviewed the articles on and I would like to say that I was very surprised.
Over years, I have seen many different articles in the field of allergy, but these articles were very interesting.
These articles were really unique, they could help many people around the world to know more about seasonal allergy, symptoms, prevention and when to seek medical advice.
These articles represent an addition in the field of Health Education not only for people with allergy but also for the whole population.

Looking for more treatment options? Find a full list of other seasonal allergy treatment options here.

Last Updated on July 5, 2023

Seasonal Allergies