A lotion which can be bought over-the-counter in chemists is just as effective at treating acne as a course of antibiotics, researchers say.
Most people are affected by acne at some point in their lives
Experts from the Universities of Nottingham and Leeds compared five treatments in the Lancet study.
They were surprised to find benzoyl peroxide lotion was as effective as antibiotic treatment.
The researchers said patients and doctors should be aware that they may not need to turn to medication.
Virtually everyone is affected by facial acne at some point in their lives.
Acne is often aggravated by hormonal changes, which is why it predominantly affects teenagers.
Lotion dries out the skin. Antibiotics treat the bacteria.
Drugs have been used extensively over the last 40 years.
But there are concerns about increasing levels of antibiotic resistance, and about the cost of treatment.
'Be more judicious'
The research team decided to compare the efficacy and cost-effectiveness of two oral antibiotics, oxytetracycline and minocycline, the topical antibiotic erythromycin, the antimicrobial lotion benzoyl peroxide, or a combination of topical erythromycin and benzoyl peroxide.
Around 650 patients, with an average age of 19, were allocated one of the five treatments.
It was found most improvement occurred over the first six weeks of any treatment.
Similar levels of self-reported improvement were also similar in all five groups.
Overall, the researcher said using benzoyl peroxide alone, or with erythromycin, were as effective as oral antibiotics.
Professor Tony Avery, head of the division of primary care at The Medical School, Queen's Medical Centre, Nottingham, said the researchers had been surprised at the effectiveness of the lotion in relation to medication.
He added: "We're not necessarily saying people don't need to take antibiotics.
"But perhaps we should try to be a little bit more judicious in how we use them."
He said one of the problems with the lotion was that people stop using it too soon because it can make their skin dry and scaly.
Professor Avery added: "If counselled about how to use them properly, and told to use moisturiser, more people would be able to tolerate them.
"Obviously acne is a very distressing condition, and different people require different treatment.
"But whatever you use, the maximum you are going to improve things is by about a half or two thirds.
"Really, with acne, you are trying to hold it at bay until the patient grows out of it."
Matthew Patey, director of the British Skin Foundation, said: "These findings are interesting and suggest an over-the-counter remedy is as effective as oral antibiotics in the treatment of mild to moderate facial acne.
"For those sufferers who feel their spots are not responding to over the counter treatments, we would recommend that they consult their GP or dermatologist at the earliest opportunity."