Are there any specific ingredients or products that cause purging?

“The new introduction of a therapeutic ingredient to treat the acne can cause an initial purge. Retinoids such as tretinoin have been shown to produce this in a minority of patients,” says Dr Chantrey. “Other ingredients include Vitamin C, retinol and other topical acids,” she adds.

Dr Jollyman concurs, adding that purging is has also been associated with many different treatments, including microabrasion and laser therapy.

Is purging something to worry about?

“No, it can be normal and many patients will see it settle within the first month of continued use of the new active ingredient,” says Dr Chantrey. “A study showed that it was more common with the use of tretinoin alone than when it was combined with other topical ingredients that have an antibacterial mechanism of action.”

How quickly does purging start and how long will it last?

“It normally starts within a few days of initiating a new treatment and can last for up to six weeks,” says Dr Jollyman. “However, it is important to persist with treatment as the skin will improve in the longer term.”

However, purging can sometimes be a result of underlying acne. “This can happen in a small subset of patients and the inflammatory lesions could be the result of that acne overcoming the anti-inflammatory activity of the active ingredient. In those cases, we monitor the patients and adjust the products being used accordingly,” explains Dr Chantrey.

Purging vs breakouts: how to tell the difference between the two