These methods can be effective in treating acne. For example, the application of anti-inflammatory creams can be effective in the early stages of inflammatory acne, but when acne is severe, the effect is not so obvious. Diet therapy and beer therapy for acne emphasize “fighting acne” by increasing or mediating the body’s immunity. Although they are effective, they require long-term adherence and may not be suitable for everyone. There is now a better way to treat acne, and that is photodynamic therapy for acne. Perhaps many beauty seekers do not quite understand this method, so here is a brief overview. Phototherapy for acne includes what we often refer to as red and blue light treatment. Red light is the longest wavelength of visible light to the naked eye and has the deepest penetration. It can penetrate about 8mm to 10mm deep under the dermis, so it is most widely used. Red and blue light is very effective in treating acne. Red light can make the skin anti-inflammatory and repair; blue light can inhibit sebaceous gland secretion, reduce the number of acne and inflammatory lesions, and promote tissue repair. Candidates for red and blue light treatment describe burying their faces in the red and blue light tubes as a bit like doing a spa facial, which feels quite warm. At present, pure blue light, combined blue and red light irradiation, and ALA-photodynamic therapy are mainly used clinically to treat acne. 1. Simple blue light irradiation is mainly used to treat mild and moderate acne. a study by Meffert et al. showed that after 10 sessions of blue light treatment for 10 minutes each, with a cumulative 325 J/cm2, acne and seborrhea symptoms could be significantly improved. A study by the American State University College of Medicine showed that blue light exposure twice a week for 1 month could destroy 90% of acne bacilli and reduce 60%-70% of inflammatory lesions, with efficacy maintained for at least 1-2 months. However, it is not effective for some sterile pore blockage, acne, scarring, and hyperpigmentation. For larger and deeper cysts or nodules also have no significant effect. 2.The combination of blue light and red light has both antibacterial and anti-inflammatory effects and is effective for mild to moderate acne. It may also directly reduce the degree of inflammation while killing the bacteria through photodynamic effects. After receiving treatment twice a week for 4 weeks, patients were evaluated at week 12 with an average reduction of 58% in acne and 76% in the number of inflammatory lesions, which is superior to the use of blue light alone. 3. ALA-photodynamic therapy is primarily used to treat moderate to severe and cystic acne. A study using ALA-photodynamic therapy for moderate trunk acne with a placebo control group showed that sebaceous gland secretion, Acinetobacter counts, and sebaceous gland volume decreased after multiple treatments, clinical symptoms improved, and the effects lasted at least 20 weeks. In addition, it was found that the effects lasted for 2-3 months after a low dose, single session of ALA-photodynamic therapy. Photodynamic therapy not only effectively treats the reduction of swelling and scarring of oily acne; but also significantly improves the symptoms of aging skin, enlarged pores, skin laxity, fine wrinkles, and dull complexion; significantly improves pigmented lesions, such as freckles, sun spots, and age spots; the overall stretching of facial skin, which can significantly reduce laxity; and repairs damaged skin, such as burns, blisters, and hyperpigmentation.