Mometasone nasal spray (Nasonex, Clarinaze): uses and cautions

Mometasone nasal spray treats the cold-like symptoms of allergic rhinitis, which means inflammation inside the nose caused by allergens such as pollen, and it is also used to treat nasal polyps, which are painless soft growths inside the nose. It is a steroid, or corticosteroid, which copies a hormone the body makes naturally. The NHS stresses these are not the anabolic steroids associated with bodybuilding.

The same drug appears in creams, ointments and scalp lotions for eczema and psoriasis and in an inhaler for asthma. A prescription-only spray called Ryaltris combines mometasone with an antihistamine.

It reduces swelling, mucus, itching and irritation in the nose, and in nasal polyps it shrinks them. The NHS says it can take a little longer to work than antihistamine sprays but the effects last longer. You will not notice an immediate change: it takes a few days to start and may take several weeks to reach full effect.

For polyps, improvement can take 1 to 2 months. For hay fever, begin at least a couple of weeks ahead of the season. If there is no improvement after 14 days, tell your doctor.

Sprays come in 25 or 50 microgram strengths, and the 25 microgram version is the one combined with an antihistamine. The NHS describes the usual hay fever dose as 1 or 2 sprays in each nostril once a day, with no more than 2 sprays in each nostril in 24 hours. For polyps, it is usually 1 or 2 sprays in each nostril once or twice a day, with a limit of 4 sprays in either nostril in 24 hours.

If you buy it rather than have it prescribed, you can use it less often once symptoms are under control, for example from 2 sprays a nostril to 1, and go back up if they worsen. With a prescription, your doctor sets the pattern. You can usually keep using it for up to 3 months, but an opened bottle should be used within 2 months or thrown away.

If you forget, use it when you remember unless the next dose is nearly due, and never add extra sprays to catch up. Using too much is unlikely to cause harm; speak to a pharmacist or doctor if worried.

A new bottle may need pumping a few times until a fine mist appears, and again if unused for a few days. Gently shake the bottle, remove the cap and blow your nose gently. Close one nostril, tilt your head slightly forward, place the nozzle in the other nostril with the bottle upright, breathe in slowly and press once. Breathe out through your mouth, repeat for a second spray if needed, then do the other nostril. Wipe the nozzle with a clean tissue and replace the cap.

More than 1 in 100 people get headaches, an unpleasant taste or smell, sneezing, nosebleeds or a dry or sore nose or throat. For nosebleeds or soreness, the NHS suggests stopping for a few days and restarting, and rinsing your mouth or brushing your teeth may help an unpleasant taste. Sneezing usually settles with use.

Serious effects are uncommon unless high doses are used for more than a few months. Call a doctor or 111 straight away for eye pain or blurred vision, which can signal glaucoma or cataract, for nose pain, sores inside the nose, or nosebleeds that will not stop. If these affect your sight, do not drive or cycle. Swelling of the lips, mouth, throat or tongue, breathing very fast or struggling to breathe, blue or pale skin, confusion or collapse require 999. Suspected side effects can be reported through the Yellow Card scheme.

Most adults can use it for polyps, rhinitis and hay fever, and children from 3 can use it for rhinitis and hay fever if prescribed. Tell your doctor before starting if you have ever had an allergic reaction to mometasone, take or have recently taken other steroids, have had nose surgery or a nose injury, have a nose or other infection, have had tuberculosis, have had glaucoma or cataracts, or have cystic fibrosis.

Speak to a pharmacist or doctor if you take HIV medicines such as ritonavir or cobicistat, or any other steroid product, such as eczema creams, asthma inhalers, tablets, injections or eye drops, because that may change side effects or the dose. Alcohol, food, contraception and driving are generally unaffected.

Children and teenagers on high doses for a long time need height and weight monitored because growth can slow. A red steroid emergency card, and a blue treatment card for very high doses, may be advised by a doctor or pharmacist, particularly if you use several steroids together such as a nasal spray and an inhaler. For adrenal insufficiency in children a similar card exists.

The NHS says the spray can be used in pregnancy because very little reaches the blood and almost none reaches the baby, and that it is fine while breastfeeding. There is no evidence of an effect on fertility.