Prophylactic Antibiotics for the Treatment of Cellulitis at Home

Can penicillin help reduce attacks of cellulitis of the leg?

What was this study about?

Cellulitis of the leg is a common, painful and serious infection of the skin and the tissues just below the skin surface. It appears as a red area of skin that feels hot and tender, and it may spread rapidly. Up to half of patients treated suffer from repeat attacks, or other difficulties such as swelling of the leg and ulceration.

PATCH aimed to find out whether low-dose penicillin given after an attack of cellulitis can prevent further attacks and complications, such as swelling and ulceration.

People with cellulitis who volunteered to take part were given either a penicillin or a placebo tablet twice a day for twelve months. Researchers monitored these people for 1½ - 2 years after that, to see if the people who took penicillin had fewer attacks of cellulitis than the people who took a placebo tablet.

What difference did this study make?


The primary outcome was the time to a first recurrence of cellulitis of the leg, in patients in patients with only one previous episode of cellulitis. 

The study suggested a substantial reduction in the number of repeat episodes that could be achieved by giving patients prophylactic penicillin for six months after an acute episode of leg cellulitis. Although this trial was limited by slow recruitment, and the result failed to achieve statistical significance, it provided the best evidence available to date for the prevention of recurrence of this debilitating condition.


The primary outcome was the time to a first recurrence of cellulitis of the leg, in patients with at least one previous episode of cellulitis. 

Long-term prophylaxis for patients with cellulitis of the leg seems to be effective and safe and could benefit all patients with recurrent disease (not just those with known risk factors). Further research is required to establish the role of prophylaxis in first episode cellulitis and the potential impact on microbial resistance in the community.

Type of study

Randomised trial

Contact details

Who funded the study?

The charity Action Medical Research funded this study.

When did it take place?

Recruitment to PATCH I started in 2006, and follow-up finished in 2011.

Where did it take place?

28 UK research sites.

Who was included?

People who have had cellulitis of the leg.