Monaz: Hello, I'm Monaz Mehta, editor in the Cochrane Editorial and Methods department. Allergic rhinitis, or hayfever, is a common condition affecting both adults and children. One suggestion for treating it is to rinse the inside of the nose with salt water and the Cochrane Review of the effects of this was published in June 2018. We asked Carl Philpott from the Norwich Medical School in the UK to tell us what he and his co-authors found.

Carl: Allergic rhinitis is swelling or irritation of the inside of the nose caused by allergies to airborne particles, such as grass pollen or dustmite. It’s accompanied by symptoms including a blocked, runny or itchy nose, and sneezing.
Various treatments have been proposed, and some of them have been assessed in Cochrane Reviews. We looked at the use of nasal saline irrigation, which is also known as nasal douche, wash or lavage, and involves rinsing the nasal cavity with saline, or salt water. The idea is that this would work by thinning the mucus in the nose, making it easier to remove, as well as removing some of the allergy particles. People can do the rinsing for themselves, using the saline on its own, or with nasal sprays or other treatments.
We looked for any studies that had tested the effects of nasal saline irrigation alone or in combination with other things, and found 14 studies involving nearly 750 patients, about two thirds of whom were children. Five studies used what is called ’very low’ volume saline, such as nasal sprays providing under 5 mL, which is less than a teaspoon full, per nostril. Two studies used low-volume, that’s between 5 and 59 mL via a syringe, and four studies used high-volume solutions, more than 60 mL per nostril. The solutions were either stronger, called hypertonic, or weaker, hypotonic; but there was too little data for us to be able detect any differences between the different volumes and concentrations.
In the comparison of nasal saline irrigation with no saline irrigation, we found benefits for symptom relief in both adults and children and little suggestion of any side effects, but this evidence was either low or very low quality. On the other hand, we were not able to determine whether adding nasal saline irrigation to other medical treatment improves the symptoms of allergic rhinitis compared to using those medications alone. And there is not enough evidence to know whether saline irrigation on its own is better, worse or the same as using steroid nasal sprays or antihistamine tablets.
In summary, the current evidence for this simple treatment for this common condition is not strong enough to be sure if it is worth using instead of other treatments but is probably sufficient to recommend that it is used along with other treatments as it is a cheap, safe and acceptable treatment. More evidence will be needed to say if it can be used as an alternative to treatments such as steroid nasal sprays and antihistamine tablets, so we’d like to see further high-quality studies to produce the evidence that will help people with allergic rhinitis make a well informed choice.”

Monaz: If you would like to read more about the current evidence, you can find the full review at Cochrane Library dot com with a search for 'nasal saline irrigation'. While if you want to find all the Cochrane Reviews of possible treatments for allergic rhinitis, simply search for the condition itself.