Background: There was a global epidemic of methylchloroisothiazolinone (MCI) and/or methylisothiazolinone (MI) contact allergy from 2009 to 2015. In response, the Thai Ministry of Public Health regulated the use of MCI/MI in cosmetics.Objective: To survey the presence of MCI/MI and MI alone, as labelled on cosmetics sold on the Thai market, before and after the ministerial directive. Methods:The presence of MCI and/or MI in leave-on and rinse-off cosmetics sold on the market, based on the labelling of ingredients in 3445 products, was analysed.Results: Before the implementation date, most leave-on products contained MCI/MI. After the regulations came into force, the only leave-on cosmetic subcategories that complied with the law were facial skin-care, sunscreen and make-up products. MCI/MI and MI alone were found on the labels of both leave-on and rinse-off products, the presence of each varying between product subcategories.Conclusions: Despite the ministerial regulations restricting their use, MCI and/or MI are still found in cosmetics sold on the Thai market. Dermatologists should be aware of this situation, and counsel patients to avoid products containing MCI and/or MI. K E Y W O R D S cosmetics, ingredient labelling, isothiazolinones, methylchloroisothiazolinone, methylisothiazolinone, skin-care products Leave-on Facial skin care 717 (35.5) 623 (36.2) 94 (31.8) Body skin care 478 (23.7) 408 (23.7) 70 (23.6) Make-up 292 (14.5) 247 (14.3) 45 (15.2) Sun care 245 (12.1) 212 (12.3) 33 (11.2) Hair care 168 (8.3)

Background Acne is a very common skin disease. Information on it is readily available and accessed by most patients. Nevertheless, they tend to have misunderstandings about the disease. Aims This study investigated Thai acne patients' perceptions of, and beliefs, about acne; their treatment‐seeking behaviors; and the data sources available to them. Patients/Methods A cross‐sectional, questionnaire‐based study was conducted among teenage and adult acne patients at the skin clinics of the Department of Dermatology and the Department of Pediatrics, Siriraj Hospital, January‐December 2017. Results A total of 330 patients with a mean age of 23.89 ± 7.19 years (range: 9‐51 years) were enrolled. Hormonal factors were the most common determinant thought to worsen acne (80.6%), followed by dirt (72.4%), inadequate sleep (65.5%), cosmetics (58.2%), and stress (55.8%), whereas frequent facial washing and exercise were the least common (4.8% each). The most common information source utilized by patients was friends (40.9%), followed by digital media (36.8%). Both males and females felt their acne greatly affected their quality of life. Before visiting the hospital, most patients used vitamin supplements and over‐the‐counter drugs as treatment. Conclusions Some patients had good conceptions of certain aspects of acne, such as the influence of hormones or food, whereas others had misunderstandings about the effects of poor hygiene on acne. Friends and websites were the most common information resources exploited by patients. Acne substantially impaired the quality of patients' lives.