Light therapy appears to reduce P. acnes numbers and disrupt sebaceous gland function, possibly on par with topical therapies. No studies directly compare light therapy with standard acne treatments. A systemic review showed that MAL-photodynamic therapy (PDT) had a 68% reduction and aminolevulanic acid (ALA)-PDT had a 59% reduction in facial acne compared to placebo after 12 weeks. However, ALA-PDT caused more erythema, pustular eruptions, exfoliation and hyperpigmentation than MAL-PDT. Intense pulsed light assisted PDT was more beneficial then intense pulsed light therapy alone. There were no significant differences between placebo, pulsed dye laser therapy and infrared laser therapy.