If you have a sinus infection, taking a course of amoxicillin, an antibiotic medication, does not help you recover faster or reduce symptoms any more effectively than taking an inactive placebo, according to a new study by Washington University School of Medicine in St. Louis, Missouri, USA, that is published in the 15 February issue of JAMA.

First author Dr Jane M Garbutt is a research associate professor of medicine at the School of Medicine. She told the media that she and her colleagues believe antibiotics are overused in primary care, and referred to efforts by the Centers for Disease Control and Prevention (CDC) to encourage more judicious use of the drugs.

"We hope this study provides scientific evidence that doctors can use with patients to explain that an antibiotic is not likely to help an acute sinus infection," said Garbutt.

Senior author Dr Jay F Piccirillo, professor of otolaryngology at the School, said:

"Our results show that antibiotics aren't necessary for a basic sinus infection - most people get better on their own."

Sinusitis means inflammation of a sinus, one of the small, air-filled spaces inside the forehead and cheekbones. The sinuses make mucus which normally drains through small tubes into the nose. Most incidences of sinusitis are due to infection and mainly affect the ones in the cheekbones.

Sinusitis is very common in the US, where 1 in 5 prescriptions for antibiotics are for treating the condition.

One reason for the CDC's campaign to encourage more judicious use of antibiotics is the increasing number of bacteria species that are developing resistance to antibiotics, so the purpose of the study was to see if this very common use of such drugs is being effective. And the results show it isn't.

Instead of straight away giving out antibiotics like amoxicillin, the one investigated in this study, the researchers suggest doctors and patients should just treat the symptoms, such as pain, fever, cough and congestion, and monitor the situation to see if further treatment is necessary.

For their study, Garbutt and colleagues examined data on 166 adults with acute sinus infection whose symptoms matched the criteria recommended by a CDC expert panel. The patients were recruited through primary care outlets in St Louis.

To be included in the study, the symptoms had to be moderate, severe, or very severe: specifically they had to include pain or tenderness in the face and sinuses, and nasal discharge lasting between 7 and 28 days.

Patients with chronic sinusitis, or serious complications from the condition were not included. Serious complications include things like ear or chest infection.

The participants were randomly assigned either to receive a 10-day course of amoxicillin, or a 10-day course of placebo. Both groups also received medications for relieving symptoms such as pain, cough, fever and congestion.

The researchers assessed the participants' symptoms at various points in the trial: at the start (day 0), and then on days 3, 7, 10 and 28. At each assessment, the participants filled in a questionnaire called the Sinonasal Outcome Test-16 (SNOT-16) which assesses a number of quality of life measures related to the condition.

The researchers also noted relapse and recurrence of symptoms and days absent from work.

The results showed that on day 3 there was no difference between the treatment and placebo group on any of the measures. On day 7, there was a small improvement in the treatment group, as assessed from the questionnaire responses.

But Garbutt said this small difference was unlikely to represent a noticeable relief in symptoms.

"Even though it was a statistically significant change, it's likely not a change that a patient would notice," said Garbutt.

The small improvement had disappeared by day 10, by which time 8 out 10 of participants in both groups reported their symptoms had either gone altogether or were very much improved.

The results showed there was no difference between the groups in the amount of symptom relief medications they chose to use.

While the study shows that antibiotics don't work for acute sinusitis, it does not answer the question of what does work for this "nasty disease" as Garbutt describes it:

"People have significant symptoms. They feel miserable and miss time from work. If an antibiotic is not going to be of any benefit, then what is? That's a question we haven't answered yet. But we are working on it," she said.

Written by Catharine Paddock PhD