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# Nasal decongestants

Alpha-adrenergic agonists that shrink swollen nasal blood vessels. Sprays work fast but cause rebound congestion if used for more than a few days.

Updated Nov 1, 2026

## What they are

Decongestants relieve the blocked nose of colds, allergic rhinitis and sinusitis. Topical imidazolines (oxymetazoline, xylometazoline) are sprayed or dropped into the nose and act within minutes; they are limited to a few days because longer use causes rebound congestion (rhinitis medicamentosa). Oral pseudoephedrine (and the less effective phenylephrine) act systemically, so they can raise blood pressure, speed the heart and cause insomnia. In many countries pseudoephedrine sales are controlled because it can be made into methamphetamine.

## Mechanism of action

Stimulation of alpha-1 and alpha-2 adrenergic receptors on the venous sinusoids and arterioles of the nasal mucosa causes vasoconstriction. Less blood pools in the mucosa, swelling falls and the airway opens. Imidazolines act directly on alpha receptors; pseudoephedrine acts mainly indirectly, releasing noradrenaline from nerve endings, with some direct action. With repeated topical use, the vessels rebound when the drug wears off and receptor responsiveness falls, so congestion returns worse.

Target: Alpha-1 and alpha-2 adrenergic receptors of the nasal mucosa

## Key points

- Topical sprays: rebound congestion (rhinitis medicamentosa) after more than a few days; oxymetazoline labels say no more than 3 days.
- Oral pseudoephedrine: hypertension, tachycardia, palpitations, insomnia, urinary retention in prostate enlargement.
- Never with MAO inhibitors (or within two weeks of stopping them): hypertensive crisis.
- Caution in hypertension, heart disease, diabetes, glaucoma, hyperthyroidism and in pregnancy.
- Swallowed imidazoline drops can cause dangerous sedation, bradycardia and low blood pressure in young children.

## Drugs in this class

- [**Pseudoephedrine** An oral decongestant that shrinks nasal vessels; it can raise blood pressure and heart rate and must never be taken… Noradrenaline release from sympathetic nerve endings (indirect), with some direct alpha action](https://durgical.com/en/pharmacology/pseudoephedrine/)
- [**Oxymetazoline** A long-acting nasal decongestant spray; used for no more than 3 days to avoid rebound congestion. Alpha-1A and alpha-2A adrenergic receptors](https://durgical.com/en/pharmacology/oxymetazoline/)
- [**Xylometazoline** An imidazoline nasal decongestant spray or drops on the WHO essential list; short use only, because of rebound… Alpha adrenergic receptors of the nasal vessels](https://durgical.com/en/pharmacology/xylometazoline/)

## Others in the class

- Phenylephrine
- Naphazoline
- Ephedrine

## Test yourself

Think of the answer, then tap the question to see it.

## What is rhinitis medicamentosa?

Rebound nasal congestion after using a topical decongestant spray for more than a few days.

## Why is oral pseudoephedrine a concern in a patient with uncontrolled hypertension?

Its sympathomimetic action constricts vessels throughout the body and can raise blood pressure and heart rate.

## Which drug class must never be combined with a decongestant?

MAO inhibitors, because of the risk of hypertensive crisis.

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Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.

Sources: [Decongestants - NHS](https://www.nhs.uk/medicines/decongestants/) (NHS, 2026); [Oxymetazoline Nasal Spray: MedlinePlus Drug Information](https://medlineplus.gov/druginfo/meds/a608026.html) (MedlinePlus (U.S. National Library of Medicine), 2016); [Pseudoephedrine: MedlinePlus Drug Information](https://medlineplus.gov/druginfo/meds/a682619.html) (MedlinePlus (U.S. National Library of Medicine), 2025).

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Source: https://durgical.com/en/pharmacology/classes/nasal-decongestants/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/pharmacology/classes/nasal-decongestants/