Acne vulgaris is a common skin condition causing blackheads and whiteheads and red spots. Acne often leads to scarring, which is extremely difficult to treat. Acne can produce significant psychological and social problems, including lower self‐esteem, anxiety, depression and low mood. Many light‐based therapies have been tried for acne vulgaris, but their effectiveness and safety are unclear. Light therapies use light with different properties, such as wavelength and intensity. The exact mechanisms are still not fully understood, but three factors are considered crucial: light, photosensitizers (i.e. molecules that absorb and are then activated by light) and oxidative stress resulting from their activation. It is thought this oxidative stress helps to damage acne causing bacteria and prevent pores blocking. This study is a review looking at trials into light treatments for acne. The researchers found that high‐quality evidence on the use of light therapies for acne is lacking. There is moderate quality evidence of the usefulness of methyl aminolaevulinate photodynamic therapy (red light) and low quality evidence on the usefulness of aminolaevulinic acid photodynamic therapy (blue light) as standard treatments for moderate to severe acne. This review reinforces the need for standardized outcome measures (ways to define if a treatment is successful), larger studies of better quality and adequate reporting of future studies.