BackgroundOver 50% of HIV infections in Thailand annually occur among men who have sex with men (MSM) and transgender women who use online applications to meet their sexual partners. We conducted a cross-sectional study assessing undetectable=untransmittable (U=U) understanding, pre-exposure prophylaxis (PrEP) awareness, sexual behaviours and factors associated with HIV knowledge among users of Hornet in Thailand.MethodsFrom November 2019 to January 2020, a survey was conducted using convenience sampling on Hornet in Thailand. HIV literacy was assessed via 22 questions, and multivariable linear regression was performed.Results960 responses were assessed; median age was 34 years, the majority were MSM (80.4%), Thai (83.8%), had at least bachelor’s degree (74.9%). Regarding the risk profiles, 39.1% reported inconsistent condom use, 15.0% used amphetamine-type stimulants, 56.9% had not taken PrEP in the last six months and 20.5% never had an HIV test. Only 22.8% thought that U=U was completely accurate. Lower HIV knowledge was associated with being from Africa (β −8.13, 95% CI −14.39 to –1.87), age of 25 years or younger (β −2.6, 95% CI −4.37 to –0.82), education less than bachelor’s degree (β −2.58, 95% CI −3.98 to –1.19), having more than one sexual partners (β −2.41, 95% CI −4.13 to –0.69), paying three or more people to have intercourse (β −2.5, 95% CI −4.26 to –0.74), not knowing one’s HIV status (β −3.56, 95% CI −5.45 to –1.68) and not answering about previous PrEP use (β −4.11, 95% CI −7.86 to –0.36). Higher HIV knowledge was associated with being from Europe (β 2.54, 95% CI 0.46 to 4.61), the Americas (β 3.37, 95% CI 0.44 to 6.30) and previous PrEP use (β 2.37, 95% CI 0.94 to 3.81).ConclusionAmong Hornet users in Thailand, the U=U message was unclear, and PrEP use was suboptimal. Large HIV knowledge gaps and high-risk behaviours were concerning. Educational campaigns in online spaces are needed to promote awareness and HIV prevention strategies.

Acanthosis nigricans is characterized by the presence of velvety hyperpigmentation of the skin over the neck and the flexural areas. Regardless of different modalities of treatment, none provides a definite standard cure. This study aims to assess the efficacy of topical 10% salicylic acid compared to 10% urea cream in treating acanthosis nigricans in adolescents. A randomized comparative, double-blind study is conducted on adolescents with acanthosis nigricans of the posterior neck. Treatment efficacy was assessed via a narrowband reflectance spectrophotometer at individual follow-up visits at weeks 2, 4, and 8, while the overall success rates were evaluated by the investigator-assessed and participant-assessed global evaluation scales (IGE and PGE). Acanthosis nigricans scoring chart (ANSC) and adverse effects are also assessed. A total of 39 participants with acanthosis nigricans enrolled and completed the study. Throughout the 8-week period of treatment, the use of 10% salicylic acid demonstrated strong effectiveness in treatment with 14.6 ± 10.6% improvement, while the 10% urea demonstrated 12.5 ± 10.9% improvement. Findings from the overall global evaluation scales were consistent with the results from the narrowband reflectance spectrophotometer. Treatment with 10% salicylic and 10% urea produced no serious local skin adverse reactions. Both medications improve neck hyperpigmentation associated with acanthosis nigricans in adolescents, in which the 10% salicylic acid and 10% urea cream demonstrate similar efficacy and safety profiles. Clinical Trials Registry: TCTR20201123003. Supplementary Information The online version contains supplementary material available at 10.1007/s00403-023-02605-6.