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BMJ Group Medical Reference

If you've got a blocked nose, medicines called decongestants can help for a short time. Decongestants help reduce the swelling inside your nose so you can breathe more easily. But the benefit is only small. Decongestants come as tablets or as sprays and drops you put up your nose.

You shouldn't use these medicines in children under age 6. To learn more, see Treating coughs and colds in children.

You can buy many different decongestant nasal sprays and drops at chemists. Some examples (with their brand names) are:

  • Ephedrine

  • Oxymetazoline (Vicks Sinex)

  • Phenylephrine (Fenox)

  • Xylometazoline (Non-Drowsy Sudafed and Otrivine).

Or you can take decongestant tablets or capsules containing pseudoephedrine (Non-Drowsy Sudafed Decongestant Tablets) or phenylephrine (Non-Drowsy Sudafed Congestion Relief Capsules).

Decongestants are also often used together with a painkiller or an antihistamine in the cold medicines you can buy in a pharmacy. There are lots available. You can take them as tablets, powders, capsules, or a syrup. Here are a few examples:

  • Paracetamol and pseudoephedrine (Non-Drowsy Sinutab)

  • Paracetamol and phenylephrine (Lemsip)

  • Pseudoephedrine and triprolidine (Sudafed Plus, Multi-action Actifed Syrup).

We found one summary of the research (a systematic review) that looked at decongestants.[11] The summary showed that a single dose of a decongestant can help relieve a blocked nose for three hours to 10 hours. But the benefit is likely to be quite small. You'll get the same small benefit if you continue to use a decongestant for three to five days. An additional study also found that a nasal spray with the decongestant xylometazoline can provide some relief to a blocked nose, although the improvement is fairly small.[12]

The studies we looked at found that side effects were no more common among people who used a decongestant than among those who used a dummy treatment (a placebo).[11][12] But we know that some decongestant sprays can irritate the lining of your nose, give you headaches, and make you feel sick.[13]

Pseudoephedrine tablets can make your heart race, make you feel restless, and make it hard to sleep.

You shouldn't use decongestant nasal sprays for longer than one week. After that, they can cause rebound congestion. This means you get a blocked nose again after you stop taking them.[14] This is more likely to happen with sprays and drops containing oxymetazoline and xylometazoline than with those containing ephedrine.

You shouldn't use decongestants if you're taking a medicine called a monoamine oxidase inhibitor. These drugs are usually used to treat depression. You could get dangerously high blood pressure if you take the two together.[14]

You should also be careful about taking decongestant tablets if you've got another medical condition, such as a heart problem, high blood pressure, or diabetes. Talk to your doctor if you're not certain which medicines you can take.

Paracetamol is an ingredient in lots of cold remedies. You must take care to avoid accidentally taking too much. A paracetamol overdose can be life-threatening.

Last Updated: October 23, 2012
This information does not replace medical advice.  If you are concerned you might have a medical problem please ask your Boots pharmacy team in your local Boots store, or see your doctor.

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