Sinus Infection & Sinusitis: Causes, Treatment & Warning Signs

A stuffy nose that will not clear, aching pressure across your cheeks and forehead, and mucus that keeps building up are the classic signs of a sinus infection — known medically as sinusitis. In most people it is caused by a virus and eases within a couple of weeks on its own. A minority, though, need proper treatment, and a rare few are a genuine emergency. Below we set out how to recognise bacterial versus viral sinusitis, the self-care that actually works, the truth about decongestant and steroid sprays, when antibiotics are worth it, and the warning signs you must never ignore. Prefer to talk it through? A registered Irish doctor is available by video or phone for €34.99, every day of the week.

Understanding sinusitis

Your sinuses are hollow, air-filled pockets behind the cheeks, brow and nose. When their lining becomes inflamed — usually after a cold — mucus stops draining freely and pressure builds, giving you a blocked or streaming nose, tenderness across the face, a dulled sense of smell, and at times a headache or mucus trickling down the back of the throat.

When this comes and goes within a few weeks it is acute sinusitis. If it grinds on beyond 12 weeks it is called chronic sinusitis, which is handled differently and really should be looked at by a doctor.

Bacterial or viral? Reading the signs

Knowing which type you have matters, because only one of them might respond to antibiotics. It is not always clear-cut, but the pattern of your illness gives strong clues.

The viral pattern (much more common)

• Arrives with a cold and generally eases off within 7 to 10 days.
• Tends to affect both sides of the face fairly evenly.
• Mucus may be clear or coloured — the shade tells you nothing reliable about bacteria.
• Antibiotics rarely change the course and are usually unnecessary.

The bacterial pattern (less common)

Bacteria are more likely to be involved when several of these apply together:

• The illness has run past 10 days with no sign of easing.
• You picked up, then took a clear turn for the worse — the “double-sickening” pattern.
• A fever of 38°C or higher that keeps going.
• Intense pain, often on one side only, in the face or upper teeth, with thick coloured discharge.

Even so, plenty of bacterial cases clear up unaided — but this is precisely when a doctor’s opinion earns its keep.

Self-care that helps at home

For the majority of sinus infections, straightforward home measures are enough while things settle:

• Simple painkillers — paracetamol or ibuprofen, if they suit you, take the edge off pain and fever.
• Salt-water rinses or saline sprays to loosen and clear mucus; safe to repeat as often as you need.
• A warm flannel held over the face to ease pressure.
• Inhaling steam from a bowl of hot water can feel comforting — mind you do not scald yourself.
• Rest and plenty of fluids to help your body recover.
• Steer clear of cigarette smoke and other irritants that inflame the lining further.

The truth about decongestant sprays

Pharmacy decongestant sprays like xylometazoline or oxymetazoline unblock a stuffy nose fast and genuinely help in the short term. But there is a firm limit: keep them to roughly 5 to 7 days, no longer. Beyond that they can trigger “rebound” congestion, where your nose blocks up again the moment the spray fades and you find yourself reaching for it just to breathe. Saline sprays and decongestant tablets do not cause this problem.

Where steroid nasal sprays fit in

Steroid sprays — such as mometasone, fluticasone or beclometasone — work differently: they calm the inflammation in the lining rather than simply clearing it. They are a cornerstone of treatment for chronic and allergy-related sinusitis, and can also help acute symptoms that refuse to lift after around 10 days. They are fine for longer-term use, but they need a few days of steady use before you feel the benefit — patience pays off. A doctor can tell you whether one is right for your situation.

Do you really need antibiotics?

For sinusitis, antibiotics are the exception rather than the rule, because most infections are viral or clear on their own. A doctor will generally reserve oral antibiotics for cases with clear bacterial features — think symptoms past 10 days with no improvement, a distinct worsening after you had started to recover, a stubborn high fever, or if you are unwell in yourself or at higher risk of complications.

If antibiotics are called for, the doctor chooses the type and dose around your history and any allergies — it is not a treatment to self-start. Taking them when they are not needed will not shorten a viral infection and brings side effects and resistance for nothing.

When it is time to see a doctor

Warning signs — go straight to the Emergency Department

On rare occasions a sinus infection spreads to the eye socket or, rarer still, towards the brain. These are serious and demand emergency attention. Get to your nearest Emergency Department without delay (or dial 112/999) if there is:

If any of these appear, do not wait for an online appointment — they need urgent, in-person assessment.

How DoxOnCall can help

When sinus symptoms drag on, keep returning, or refuse to budge with self-care, a registered Irish doctor can review you by video or phone, guide you on the right sprays and self-care, and — where clinically suitable — send a prescription (antibiotics included, when they are truly warranted) straight to your chosen pharmacy. A single flat fee of €34.99 covers the consultation, with same-day slots usually available, seven days a week.

Frequently asked questions

Related: if your symptoms are seasonal — sneezing with itchy, watering eyes — it may be hay fever rather than a sinus infection; see our hay fever treatment guide.

This information is general guidance and does not replace personal medical advice. Always seek care tailored to your own circumstances, and treat the warning signs above as an emergency.