Can antibiotics prevent cellulitis from coming back?

Various groups of researchers have looked into the possible advantages and disadvantages of preventive treatment with antibiotics in people who keep getting erysipelas or cellulitis infections. The researchers found five studies with a total of about 500 patients.

Two of the five studies were particularly conclusive because quite a lot of people took part in them and they were designed and carried out well. Both of the studies also kept in touch with the participants for three years to see whether the skin infection returned. This meant that they were able to provide information about how well the antibiotics worked in the long term.

In one study, the participants had cellulitis for the first time. They were randomly assigned to two groups. One group was given penicillin for six months, and the other was given a placebo (fake drug) for six months. The dose of penicillin taken was 500 mg per day (two 250 mg tablets), which is quite a small dose. In the other study, participants had to have had cellulitis at least twice already. The treatment was the same as in the first study, but lasted twelve months instead.

When analyzed together, the results of these two studies showed that taking penicillin over a long period of time prevents further infections. During the three years in which the researchers stayed in touch with the study participants,

• 43 out of 100 people who were given the placebo developed a new bacterial skin infection.
• 32 out of 100 people who were given penicillin developed a new bacterial skin infection.

In other words, penicillin prevented 11 out of 100 people from getting another infection during this time period.

Both studies also looked into how common side effects were. The researchers were especially interested in nausea, diarrhea, rashes and fungal infections because these side effects are often associated with antibiotics.

The results showed that these side effects weren't more common in the penicillin group than they were in the placebo group. So, if people take penicillin and have diarrhea, for instance, it doesn't necessarily mean that the diarrhea was a side effect of the medication.

The reason why the antibiotics were so well tolerated in the studies might be because they were taken in such small doses. But even low-dose antibiotics might still cause side effects sometimes. Although a few hundred people took part in the studies, the total number of participants isn't enough to draw conclusions about rare side effects.

Some people aren't able to take penicillin at all because they are allergic to it – but this is very uncommon. If you take antibiotics, it's always a good idea to find out how to use them properly. The incorrect use of antibiotics can make bacteria become resistant to these drugs, and then they no longer work properly.