Sinusitis: How Long It Lasts, When It Is Really Bacterial and When Antibiotics Help

Is sinusitis viral or bacterial, and how long does it last?

The short answer is that it is usually viral and it usually clears on its own. Your sinuses are small air filled spaces inside the bones of your face, around the nose, behind the forehead and under the eyes. When you catch a cold, the lining of the nose and sinuses swells together, the narrow drainage openings block, and mucus collects inside. That is what produces the heavy face, the blocked nose and the thick discharge.

This cold related inflammation is extremely common and happens to some degree with most colds. The 2015 adult sinusitis guideline from the American Academy of Otolaryngology states that only a small share of viral episodes, roughly 0.5 to 2 percent, go on to become a bacterial infection. In practical terms, most people who buy an antibiotic from the pharmacy for their sinuses do not need one.

Symptoms usually peak on day two or three and then ease gradually, and most people feel clearly better somewhere between day seven and day ten. Some blockage, a mild cough or a sense of pressure can hang on for up to three weeks, and that alone does not mean the infection has turned bacterial. What matters is the direction of travel: are you improving from one day to the next, or are you flat or getting worse?

Doctors call it acute sinusitis when it lasts less than four weeks, and chronic sinusitis when symptoms continue for 12 weeks or more. The two have different causes and different treatment, and this guide covers both.

Sinusitis symptoms: how do you know it is your sinuses?

Doctors rely on four core symptoms: a blocked or congested nose, thick coloured discharge from the front of the nose or dripping down the back of the throat, pain or pressure in the face, and a reduced sense of smell. Two of these, including either blockage or discharge, are enough for a doctor to start thinking about sinusitis.

Sinus pain has a recognisable character. It is usually a dull, heavy pressure over the cheeks, between the eyes or across the forehead, and it gets worse when you bend forward, for example when tying your shoes or bowing during prayer. You may also notice an ache in the upper back teeth, bad breath, tiredness and a mild temperature.

Many people mix up sinusitis, a common cold and nasal allergy, because the symptoms overlap. The table below sets out the clearest differences. Treat it as a rough guide rather than a diagnosis, because a doctor decides on the examination and the full story.

The 10 day rule and double worsening: when is it bacterial?

There is no simple blood test in an ordinary clinic that separates viral from bacterial sinusitis, so international guidelines rely on how the symptoms behave over time. The 2012 guideline from the Infectious Diseases Society of America (IDSA) and the 2015 American adult guideline agree on two main patterns.

The first is the 10 day rule: symptoms lasting ten days or more with no improvement at all. Notice the words no improvement. Someone who is slowly getting better on day eleven is not in the same position as someone who has not changed. The second is double worsening: you start with an ordinary cold, improve for a few days, then suddenly become worse than you were at the start, with a new fever, sharper facial pain or thicker discharge.

The IDSA guideline adds a third, less common pattern: a severe start from day one, with a temperature of 39 degrees Celsius or higher plus pus like discharge or marked facial pain for three to four days in a row. In any of these three situations a bacterial cause becomes a real possibility and it is worth seeing a doctor rather than waiting.

Green or yellow mucus is not enough on its own. The colour comes from immune cells fighting any infection, viral or bacterial, and it usually appears in the first days of a plain cold as well.

When do antibiotics help sinusitis, and when do they do harm?

Even when sinusitis is bacterial, an antibiotic is not always needed straight away. The 2015 American guideline allows doctors to offer watchful waiting for uncomplicated cases, provided the patient can be followed up, and to start an antibiotic if things worsen or fail to improve within seven days. The reason is that many mild bacterial cases also clear by themselves, while antibiotics carry real side effects such as diarrhoea and rashes.

When a doctor decides an antibiotic is needed, the usual first choice in guidelines is amoxicillin, alone or combined with clavulanic acid, typically for five to ten days in adults. The drug and the length of the course are your doctor's decision, based on your history and any drug allergy. Do not use a leftover pack from a previous illness, and do not finish a course that was prescribed for a relative or a neighbour.

In much of the region an antibiotic can be bought at a pharmacy without a prescription, which makes it tempting to start one on day three of a cold. The trouble is that an antibiotic does nothing to speed recovery from a virus. It exposes you to side effects and adds to antibiotic resistance, which makes your own treatment harder on the day you really do need it.

What helps in every case: rest and warm drinks, common pain and fever relievers used according to the pack or your pharmacist, salt water rinses, and nasal steroid sprays, which doctors sometimes prescribe. Decongestant sprays that open the nose within minutes help for a few days only. Their packs usually say not to use them for more than three days, because overuse causes rebound congestion that is worse than the original.

How to rinse your nose with salt water safely

Nasal rinsing with saline is one of the best home treatments for both acute and chronic sinusitis, and the 2020 European position paper treats it as a cornerstone of chronic sinusitis care. It washes out thick mucus, dust and allergens, calms swelling of the nasal lining and helps the sinuses drain.

There is one condition you must not compromise on, and that is the water. In very rare but almost always fatal cases, an amoeba that lives in warm water, Naegleria fowleri, can travel from the nose to the brain. In 2011 two people in Louisiana died after rinsing their sinuses with tap water using a neti pot, and the amoeba was found in the water at both homes. In Karachi, a 2011 report described 13 cases in people who had never been swimming, and the researchers concluded that tap water entering the nose was the likely route.

That matters in this region in particular, where household water sits in rooftop tanks heated by the summer sun, and where supply in some cities is intermittent and chlorine levels can drop. The fix is simple. Use water that has been boiled for a full minute and cooled until lukewarm, or distilled or sterile water from a pharmacy. Bottled drinking water is better than tap water but is not always sterile, so boiling it first remains the safest habit.

Follow the steps below, and use the ready made saline sachets sold in pharmacies according to the instructions on the box, because they are mixed to the right strength and usually contain sodium bicarbonate, which reduces stinging.

Dust storms, air conditioning and allergies: why sinus symptoms keep coming back

If your nose blocks and your sinuses feel heavy every time a dust storm blows in or the seasons turn, the cause is probably not repeated infection but nasal allergy, known as allergic rhinitis. Allergy keeps the nasal lining swollen, which narrows the sinus openings, and every cold then has a better chance of turning into a longer and heavier bout of sinusitis.

A Saudi systematic review published in 2022 pooled 16 studies covering almost 32,000 people. It estimated that allergic rhinitis affects about 21 percent of the population, with higher rates in cities than in rural areas. Dust was one of the most common triggers, alongside perfume, air conditioning and changes in the weather. That picture will be familiar to anyone in the Gulf, Iraq or the Levant, where dust waves recur and people spend long hours in dry, air conditioned rooms.

Treating the allergy properly cuts the number of sinus flare ups. That means rinsing your nose after dust exposure, wearing a well fitting mask on storm days, keeping windows shut and cleaning air conditioner filters regularly, and keeping incense, cigarette and shisha smoke out of the house. A doctor may prescribe a nasal steroid spray for regular use or an antihistamine. These medicines work slowly and can take weeks to show their full benefit.

Chronic sinusitis and nasal polyps: when symptoms never quite go

If blockage, loss of smell and discharge continue for twelve weeks or more, that is chronic sinusitis, which is a long term inflammatory condition more than an infection. It cannot be diagnosed from symptoms alone. It needs an examination of the inside of the nose with an endoscope by an ear, nose and throat (ENT) specialist, or in some cases a CT scan of the sinuses.

Some people develop soft, grape like growths inside the nose called nasal polyps, which block the airway and can almost wipe out the sense of smell. A study of 660 patients with chronic sinusitis at a university hospital in Riyadh, published in the Saudi Medical Journal in 2023, found that 67.7 percent had polyps, 32 percent had asthma and 10 percent were sensitive to aspirin. These are patients at a specialist hospital, so they represent the more severe end, but the figures are a reminder that sinus disease and asthma often travel together.

Treatment for chronic sinusitis is a long game. The foundation, according to the 2020 European position paper, is regular saline rinsing and a daily nasal steroid spray used over the long term. Some patients need short courses of oral steroids, endoscopic surgery to widen the sinus openings, or newer biologic medicines for severe disease with polyps. Repeated courses of antibiotics are usually not the answer for chronic sinusitis.

If you have asthma and a nose that never clears, tell your doctor, because treating the nose well can also improve asthma control.

Is it really sinusitis? Tooth pain, migraine and other look-alikes

Not every facial pain is your sinuses. The roots of the upper back teeth sit right against the floor of the maxillary sinus under the eye, so sinusitis can make several upper teeth ache at once. It also works the other way: an abscess in an upper molar, a recent extraction or a root canal problem can spread infection into the sinus itself, causing one sided sinusitis with a foul smell that will not settle until the tooth is treated.

Migraine is the most common mix up. Many people who say they get a sinus headache every month actually have migraine, because migraine can cause pain across the forehead and around the eyes with stuffiness, watery eyes and a slight runny nose. If your headaches come in attacks, with nausea or sensitivity to light and sound, and without thick discharge or loss of smell, think about migraine and mention it to your doctor, because the treatment is completely different.

Other look-alikes include tension headache, jaw joint pain in people who clench or grind their teeth at night, and a deviated nasal septum, which causes constant blockage on one side. The table below can help you sort your thoughts before an appointment.

Warning signs: when does sinusitis need a hospital today?

Complications of sinusitis are rare but serious, because the sinuses sit right next to the eye socket and close to the brain. Infection can spread into the tissues around the eye, into the membranes around the brain or into the bone of the forehead. These need hospital care, usually intravenous antibiotics and an urgent scan, and delay can sometimes cost a person their sight.

Be especially alert if you have poorly controlled diabetes, take medicines that weaken the immune system or are having chemotherapy. In these groups certain fungi can cause a fast, aggressive sinus infection. Warning signs include black crusts inside the nose, numbness of the face or severe pain on one side. This cannot wait until tomorrow.

For everyday situations, see a doctor if symptoms last ten days without improving, if you get worse after getting better, if you have more than three or four episodes a year, or if symptoms go on beyond three months. If a pharmacy is the first place you can reach, ask the pharmacist to check your temperature and to ask how long you have been unwell before handing over any antibiotic.

Sources

• Rosenfeld RM, Piccirillo JF, Chandrasekhar SS et al: Clinical practice guideline (update): adult sinusitis, Otolaryngology--head and neck surgery : official journal of American Academy of Otolaryngology-Head and Neck Surgery, 2015
• Chow AW, Benninger MS, Brook I et al: IDSA clinical practice guideline for acute bacterial rhinosinusitis in children and adults, Clinical infectious diseases : an official publication of the Infectious Diseases Society of America, 2012
• Fokkens WJ, Lund VJ, Hopkins C et al: European Position Paper on Rhinosinusitis and Nasal Polyps 2020, Rhinology, 2020
• Aburiziza A, Almatrafi MA, Alonazi AS et al: The Prevalence, Clinical Picture, and Triggers of Allergic Rhinitis in Saudi Population: A Systematic Review and Meta-Analysis, Journal of asthma and allergy, 2022
• Alfallaj R, Obaid SB, Almousa H et al: Demographic and clinical profile of patients with chronic rhinosinusitis in Saudi Arabia, Saudi medical journal, 2023
• Shakoor S, Beg MA, Mahmood SF et al: Primary amebic meningoencephalitis caused by Naegleria fowleri, Karachi, Pakistan, Emerging infectious diseases, 2011
• Yoder JS, Straif-Bourgeois S, Roy SL et al: Primary amebic meningoencephalitis deaths associated with sinus irrigation using contaminated tap water, Clinical infectious diseases : an official publication of the Infectious Diseases Society of America, 2012