Patient guide to sinus infection

About sinus infection

A sinus infection can develop when a cold spreads to the lining of the sinuses. In most cases, the cause is a virus. In rare cases, bacteria are the cause.
Typical symptoms are pain or pressure in the forehead or upper jaw. The nose becomes blocked and produces discharge. Fever and feeling unwell are common.

A sinus infection can cause pressure and pain in the forehead and over the cheeks.

Treatment of sinus infection

A sinus infection is usually treated at home with a standard nasal spray and possibly salt water rinsing. Antibiotics have little effect on sinus infections and are only used when there are signs that bacteria are the cause. This is assessed at the clinic.

Nasal spray

Nasal spray reduces swelling in the lining so that the drainage passages from the sinuses open up.
You can buy nasal sprays over the counter, for example Otrivin or Zymelin.
It is important not to use these nasal sprays for more than 10 days, as prolonged use can itself damage the lining of the nose.

Rinsing with salt water

It is helpful to rinse your nose with salt water about 30 minutes after using nasal spray.
You can use a neti pot or a special plastic rinsing bottle from the pharmacy.
The salt water you use to rinse your nose must be lukewarm and have the same salt concentration as the body, meaning 0.9 per cent. If the water does not have the same salt concentration as the body, it can irritate the lining.
You can buy salt water at the pharmacy or make it yourself by dissolving one level teaspoon of fine table salt in half a litre of lukewarm, clean water.
In Denmark, you can normally use drinking water straight from the tap when making salt water for nasal rinsing. If you are unsure about the water quality, you should use sterile or boiled water.

Pain relief

• Sleeping with your head slightly higher than normal may help.
• For pain, you can use painkillers, for example paracetamol tablets, 1 g no more than 4 times daily.

Antibiotic treatment

• Follow our instructions for taking antibiotics. These are also on the medicine box.
• Read the patient information leaflet, and contact us if you suspect serious side effects.
• Always complete the full course of treatment, even if the symptoms disappear during it.

Follow-up

• If you do not notice any improvement within a week, contact us.
• If antibiotic treatment does not work after a few days, contact us again.

Preventing sinus infections

If you have had repeated sinus infections, you can do the following:

• Prevent colds with good hand hygiene and avoid close contact with people who have a cold.
• Use nasal spray as a preventive measure when you get a cold.
• Rinse your nose regularly with salt water.

Clinically updated 12 January 2026