Common colds: Can antibiotics help?

The adverse effects of antibiotics probably outweigh the benefits of antibiotics for uncomplicated colds. They might be worthwhile only when a cold does not get better as fast as usual or there is bacterial infection.

The common cold is usually caused by viruses. Because antibiotics are only work against bacteria, and not viruses, you can usually expect no benefit from these medications for a cold. Sometimes when someone has a cold, a bacterial infection also sets in. In that case, antibiotics might be able to help with that infection.

To try and be more clear about the pros and cons of treating colds with antibiotics, researchers from the Cochrane Collaboration looked for trials on the effects of antibiotics, including adverse effects. They found 13 trials altogether, which included otherwise healthy adults.

Their analysis showed that only a small proportion of the people with the cold benefited from antibiotics. After a week, about 75 out of 100 people taking antibiotics were better (75%). But 65 out of every 100 taking placebos (dummy tablets) were better too (65%). This means that antibiotics only helped about 10 people out of every 100 who took them.

With a relatively small proportion of people benefiting, the adverse effects are particularly important. The studies showed that on average, from 8 to 9 out of every 100 people who took antibiotics had an adverse effect. These were usually diarrhoea or other gastrointestinal complaints like nausea. Other common adverse effects of antibiotics are skin rashes and vaginal thrush.

There were, however, two groups of people who could benefit more from antibiotics for the cold. The first are people whose colds have been going on for more than one week. The second group are people with coloured nasal mucus. This can be a sign of bacterial infection, although it does not always mean there is a bacterial infection.

With almost as many people getting side effects as experiencing a benefit, antibiotics are not a good prospect for treatment for the common cold. Many experts argue that antibiotics should only be used when they have an important benefit. They are concerned that overuse in minor illnesses could also encourage the development of antibiotic resistant organisms. The development of these bacteria can mean that antibiotics will not be so effective for serious conditions.

© IQWiG (Institute for Quality and Efficiency in Health Care)