The outcomes that matter most

Change of acne severity during and at the end of treatment (investigator reported or self-reported, reduction in inflammation and number of acne lesions) were prioritised by the committee as critical outcomes because they indicate whether the treatment is efficacious. Disease-specific health-related quality of life was another critical outcome because it indicates whether the person with acne vulgaris perceives an improvement in acne symptoms. Skin-related adverse events were chosen as a critical outcome and satisfaction with treatment as an important outcome because they indicate whether the intervention is safe in the short-term and the acceptability of the intervention.

The quality of the evidence

The quality of the evidence ranged from very low to moderate, with most of the evidence being of a low quality. This was predominately due to risk of bias of individual studies and imprecision of the effect estimates. Two studies were sponsored by industry.

Benefits and harms

Overall, the evidence on the use of skin care products was very limited. The committee recommended that advising the use of a syndet skin cleansing product for acne vulgaris affected areas, ideally twice daily, should be considered as the evidence suggests that this reduces inflammatory and non-inflammatory acne lesion counts. These bars have a non-alkaline (skin pH neutral or slightly acidic), whereas traditional soap bars are alkaline, therefore syndet skin cleansing products are less irritant to the skin than traditional soap bars. The committee also discussed that, although the research was carried out on a syndet bar, many syndets are now available in different formulations such as liquid or foam, and they agreed that different formulations are probably similarly effective. The committee discussed that the costs of syndets varies and noted that it would be reasonable to try the cheapest syndet in the first instance.

No relevant evidence on the use of other skin-care products such as oil-free products or make-up was identified. However, the committee agreed that it was important to say something about the use of skin care products as many people affected by acne vulgaris are concerned about them. Therefore, based on their knowledge and experience, they recommended that people with acne vulgaris should be advised to avoid applying oil-based and comedogenic (i.e. likely to block pores) products whenever possible as these could worsen their acne vulgaris. They agreed that oil-based and comedogenic skin care products (moisturisers and sunscreens) should be avoided. They also recommended that people with acne vulgaris using make-up should be advised to avoid oil-based and comedogenic products and to remove make-up at the end of the day. They discussed that in their experience oil-based and comedogenic products can make acne vulgaris worse because acne is typified by excessively oily skin and skin prone to blockage of pores. The committee discussed what to use for make-up removal. They agreed that this could be part of skin cleansing advice, using a non-alkaline (skin pH neutral or slightly acidic) syndet or in addition to it, if it is a specific area of the face (as in removal of eye make-up) or a specific type of make-up (for example long lasting make-up used in theatres) which may require a different type of cleanser. Given the lack of evidence, the committee decided that they could not be prescriptive about the products that should be used for make-up removal.

There was limited evidence of low quality on the use of acidic skin cleansers and benzoyl peroxide-based face washes. Although there was moderate quality evidence for the outcome of participants satisfied or very satisfied with the benzoyl peroxide from 1 study, the committee agreed that a recommendation could not be made based on this outcome.

Furthermore, there was little evidence of benefit for other outcomes based on low quality evidence. Therefore, the committee did not make a recommendation about these products.

The committee discussed whether a research recommendation should be made for this topic. Clinicians are frequently asked for advice regarding skin care, such as what is appropriate and effective in people with acne vulgaris. Therefore, it is an important topic for people with acne vulgaris. Due to the limited evidence the committee decided to prioritise this for a research recommendation (see appendix L).