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

They can be taken to ease the symptoms of congestion when you have:

• a common cold
• hay fever, or other allergic reactions, such as to dust mites
• the flu
• sinusitis

Many decongestants can be bought over the counter in pharmacies without a prescription. They are available as tablets or a nasal spray.

How decongestants work

The skin lining in your nose contains many tiny blood vessels. If something irritates this lining, such as an infection or allergy, more blood flows to these vessels as part of your body’s immune response, making them swell.

This can block your nasal airway, making it difficult for you to breathe through your nose.

Decongestants reduce swelling of the blood vessels inside your nose. This helps to open up your nasal airway, making breathing easier.

However, although decongestants can help you to breathe more easily, they cannot cure the underlying cause of your blocked nose, such as a cold or allergy.

Things to consider when using decongestants

Decongestants are not usually recommended for children aged under 12, for women who are breastfeeding and for people with certain health conditions, such as high blood pressure.

Speak to your pharmacist or GP if you are unsure whether to take decongestants.

Read more about issues you need to consider before taking a decongestant.

It is not recommended to use decongestants for more than seven days, as they can cause your nose to become more blocked once you stop taking them (rebound congestion).

If your symptoms fail to improve after this time you should contact your GP.

Side effects

When side effects occur after taking decongestants, they tend to be mild. These can include:

• dry mouth
• headache
• feeling sick

More serious side effects have been reported, such as hallucinations (seeing and hearing things that are not real) and a severe allergic reaction (anaphylaxis), but these are rare.

Read more about the side effects of decongestants.

Interactions

It is now commonplace for decongestants to be sold as part of an “all-in-one” cold, flu or hay fever remedy, where the decongestant medication is also combined with painkillers, such as ibuprofen, paracetamol or with antihistamines (used to treat allergies).

It is important to carefully read the patient information leaflet that comes with your medication, as it could be dangerous to take one of these “all-in-one” remedies and then go on to take extra ibuprofen, paracetamol or antihistamines.

You should not take decongestants if you are taking a type of antidepressant called a monoamine oxidase inhibitor, as this can cause a dangerous rise in blood pressure.

Decongestant medicines don’t often cause side effects, and any side effects you may have are likely to be mild.

Reported side effects of decongestants include:

• irritation to the lining of your nose
• a skin rash
• headaches
• feeling sick or being sick
• dry mouth
• restlessness or anxiety
• tremor (uncontrollable shaking and trembling)
• problems sleeping (insomnia)
• rapid and/or irregular heartbeat
• noticing your heart beating inside your chest (palpitations)
• in men – difficulty passing urine

These side effects should pass once you finish taking the medication.

More serious and rarer side effects include:

• hallucinations (seeing and hearing things that are not really there)
• experiencing a combination of vomiting, palpitations and headache – this could be due to a sudden rise in blood pressure

If you experience these rarer side effects, stop taking the medication and seek medical advice.

Very rarely you may experience a serious allergic reaction (anaphylaxis), such as swelling of the throat, that can cause breathing difficulties, as well as swelling of the lips and the appearance of a red skin rash.

Anaphylaxis is a medical emergency. Call 999 immediately and ask for an ambulance.

Most people can use decongestant medicines, although they may not be suitable for everyone.

Before taking decongestants, always read the patient information leaflet that comes with the medicine.

Babies and children

Decongestants should not be given to children under the age of six and are not recommended for children under 12, unless advised by a GP or pharmacist.

If your child has a stuffy nose, breathing in steam with added essential oils, such as eucalyptus or rosemary, may help relieve it. Make sure you supervise your child when doing this, due to the accidental risk of scalding.

For babies, you may find that placing a few drops of saline (salt water) just inside their nose, before they feed, will help relieve a blocked nose. Saline drops are available from pharmacies.

Pregnancy and breastfeeding

It is unclear whether decongestants are entirely safe to take during pregnancy, especially during the first three months.

Therefore, their use is not usually recommended unless you are advised by your GP or midwife.

Some decongestants, such as oxymetazoline, are safe to take if breastfeeding, but others, such as phenylephrine, may not be recommended.

It is important to carefully read the information leaflet that comes with your medication.

When to avoid decongestants

It may not be safe to take decongestants if you have certain health conditions. Talk to your GP before using a decongestant if you:

• have diabetes
• have high blood pressure (hypertension)
• are being treated for an overactive thyroid gland (hyperthyroidism)
• have an enlarged prostate gland
• have liver damage, such as scarring of the liver (cirrhosis)
• have kidney disease
• have heart disease or circulation problems
• have glaucoma (a build up of fluid inside the eye)
• are taking a monoamine oxidase inhibitor (a type of antidepressant medication)

You should also talk to your doctor or pharmacist if you are already taking any other medications.