Decongestants are a type of medicine that can provide short-term relief for a blocked or stuffy nose (nasal congestion).

They can help ease the symptoms of conditions such as colds and flu, hay fever and other allergic reactions, and sinusitis.

They work by reducing the swelling of the blood vessels in your nose, which helps open up the airways.

This page covers:

Types of decongestants

Who can take decongestants

How to use decongestants

Side effects of decongestants

Interactions with other medications

Types of decongestants

Decongestants are available as:

  • nasal sprays
  • tablets or capsules
  • liquids or syrups
  • flavoured powders to dissolve in hot water

Some products may just contain decongestant medication, but many are sold as "all in one" remedies that contain decongestants, painkillers and/or antihistamines.

Most decongestants can be bought over the counter from pharmacies without a prescription.

Who can take decongestants

Most people can use decongestants safely, but they're not suitable for everyone.

They shouldn't be used by the following groups of people without getting advice from a pharmacist or GP first:

  • babies and children – decongestants shouldn't be given to children under six years old and should only be used by children aged 6-12 on the advice of a GP or pharmacist
  • pregnant and breastfeeding women – it's not clear whether it's safe to take decongestants if you're pregnant or breastfeeding, so you should only use them if advised by a healthcare professional
  • people taking other medications (see Interactions with other medications below)
  • people with diabetes
  • people with high blood pressure
  • people with an overactive thyroid gland (hyperthyroidism)
  • men with an enlarged prostate
  • people with liver, kidney, heart or circulation problems
  • people with glaucoma (increased pressure in the eye)

The patient information leaflet that comes with your medicine will state who shouldn't use it and who should seek advice before using it.

How to use decongestants

Most decongestants should only be used three or four times a day.

Check the patient information leaflet that comes with your medicine for advice about how much to take and how often to take it. If you're unsure, ask a pharmacist for advice.

Decongestant nasal sprays shouldn't be used for more than a week at a time because using them for too long can make your stuffiness worse.

Speak to your GP if your symptoms fail to improve after this time.

Side effects of decongestants

Decongestant medicines don't usually have side effects, and any side effects you may experience are usually mild.

Possible side effects can include:

  • irritation of the lining of your nose
  • headaches
  • feeling or being sick
  • a dry mouth
  • feeling restless or agitated
  • a rash
  • uncontrollable shaking (tremor)
  • problems sleeping (insomnia)
  • a rapid and/or irregular heartbeat (arrhythmia)
  • noticeable heartbeats (palpitations)
  • in men, difficulty passing urine

These side effects should pass after you stop taking the medication.

More serious side effects can also occur, such as hallucinations and severe allergic reactions (anaphylaxis), but these are very rare.

Interactions with other medications

Seek advice from a pharmacist or GP before taking decongestants if you're taking other medications. Decongestants can increase or decrease the effect of some other medications.

For example, taking decongestants alongside a type of antidepressant called a monoamine oxidase inhibitor (MAOI) can cause a dangerous rise in blood pressure.

It's also important to be wary of taking other medications if you're using an "all in one" decongestant remedy.

These products contain additional painkillers and/or antihistamines, so it could be dangerous to take extra separate doses of these medicines at the same time.

Page last reviewed: 03/03/2016

Next review due: 03/03/2018