Disclaimer: This page focuses on a polarising topic about sex and the use of illicit drugs. This information is not meant to condone specific activities, but to encourage individuals — everyday people, health providers and advocates — to have an open and nonjudgmental dialogue about challenging topics that are part of today’s culture and may contribute to new HIV diagnoses. ViiV Healthcare does not condone the use of illegal drugs.

A pro-pleasure or sex-positive mindset encourages people to enjoy consensual and fulfilling sexual experiences, free from stigma or judgement. Sex can be a positive thing in people’s lives, but it’s important that people’s sexual choices are respected so that everyone can explore their sexuality safely and consensually.

At ViiV Healthcare, we aim to promote sex positivity whilst raising awareness about potential concerns, including those relating to HIV. This creates a more understanding and supportive space, helping promote safer and better informed sexual practices.

Sexual activities associated with being more likely to acquire HIV may include: chemsex, condomless sex, group-sex, anonymous sex, and having multiple sexual partners without consistent condom/PrEP use or knowledge around their HIV status.1 In this page, we focus on chemsex, covering why people engage in chemsex, how chemsex relates to HIV transmission, how we should approach talking about the topic, and how to support individuals involved in chemex.

Learn more about other uninhibited behaviours and HIV prevention strategies in our dedicated page.


‘Chemsex’ is a combination of the words ‘chemical’ and ‘sex’— the term is commonly used across Europe and Asia.2,3 Chemsex refers to the use of drugs, particularly psychoactive and disinhibiting substances, in the context of sexual intercourse.4 Psychoactive substances are chemicals that alter brain function and result in changes in perception, mood, consciousness, cognition, or behaviour.5

Chemsex can also be referred to as party and play (PnP) in the U.S. and Australia, whilst in South East Asia, common alternative terms include ‘high fun’ or ‘chemfun’.3,6 The term ‘high and horny’ (HnH) is also used globally on mobile dating apps to convey the meaning of chemsex.3

Individuals engaging in chemsex often use substances such as crystal methamphetamine, mephedrone (MCAT), gamma-hydroxybutyrate or gamma-butyrolactone (GHB/GBL).7 Some people may also use ecstasy (MDMA), poppers (alkyl nitrites), and ketamine to further enhance or prolong their sexual experiences, often in combination.8

Additionally, the term ‘chemsex parties’ describes events where individuals gather to engage in sexual activities under the influence of psychoactive substances.6 A chemsex party can occur in various settings, including private homes, clubs, or other social spaces.9

Chemsex is currently on the rise. In 2021, estimates from nine countries in Asia suggest that between 3 to 31% of gay men and other men who have sex with men (MSM) engaged in chemsex in the past year.8 Experts believe the rise is due to the involvement of digital technologies, with an increase in the use of dating apps and social media facilitating the growth of connecting people with each other for chemsex parties and meetups.6 In Europe, chemsex rates vary, with the highest proportion in the UK at 32.8%, followed by Spain (23.0%), Greece (19.2%), and Italy (11.9%).10 In the USA, 10.3% of MSM reported chemsex drug use in the past 12 months.11

Is chemsex safe?

Chemsex is generally considered unsafe. The drugs that are usually involved in chemsex can impair decision-making, leading to a loss of inhibition during sexual encounters.6 This may be a pleasurable experience for many, but for some it could lead to more unsafe experiences. For instance, a lack of communication may compromise sexual boundaries and consent, making individuals more prone to making choices that they might later regret.2

Other potential dangers due to lowered inhibitions may include not taking antiretrovirals (ARVs) for people living with HIV, or not taking pre-exposure prophylaxis (PrEP) or post-exposure prophylaxis (PEP) for those without HIV.4,7

Chemsex drugs can also be injected in a behaviour called ‘slamming’, or ‘slamsex’.7 Slamsex brings with it additional potential for HIV and hepatitis C transmission if needles or other injecting equipment is shared.7

While often pleasurable, the experience of chemsex may also contribute to a dependency on substances, leading to addiction and associated health and social issues.6,12 Individuals under the influence of psychoactive substances may be more likely to engage in condomless sex, increasing the likelihood of sexually transmitted infections (STIs), including HIV.7


When discussing people engaging in chemsex, it's crucial to approach the discussion with a sensitive pro-pleasure and sex-positive mentality, avoiding judgmental language, and acknowledging the diverse motivations behind these behaviours.13

Some reasons for engaging in chemsex may include:

  1. Enhanced pleasure - Some individuals use psychoactive substances to enhance sexual pleasure, intensify sensations, or experiment with different experiences.4
  2. Social connection - Chemsex may be a way for individuals to connect socially, either within specific communities or as a form of bonding with others who share similar interests.4
  3. Escapism - The altered state induced by substances can provide a temporary escape from negative feelings (i.e. stress, anxiety, loneliness, lack of confidence, low self-esteem, internalised homophobia, and stigma about one's HIV status).4 Chemsex typically lasts longer than a routine sexual encounter, often lasting hours and sometimes even days.4
  4. Exploration of sexuality - Chemsex might be a way for individuals to explore and express their sexuality, engage in new or different sexual activities, or challenge societal norms.14
  5. Coping mechanism - For some, engaging in chemsex may serve as a coping mechanism for dealing with emotional or psychological issues, although this strategy has its own risks.4

Gay men and other MSM are often stigmatised for engaging in chemsex, but it should be noted that although it is common in these communities, substance use during sex is not exclusive to any particular sexual orientation.3 People of all genders and sexualities, including straight men and women, trans women and non-binary people may also participate in chemsex.3

Services should opt to combat this stigma and provide resources and information about chemsex, as well as shattering misconceptions surrounding the LGBTQIA+ community. This community can experience dual stigma due to both their sexual orientation and substance use, compounding the intense challenges that they already face.15


At ViiV, we aim to empower individuals to have open dialogue and, if engaging in chemsex, to do so as safely as possible whilst understanding the risks.

Our ‘Science on the Sofa’ series aims to change the way we talk about HIV by breaking down complex concepts to make science accessible to everyone. For too long, the latest in HIV research and science was limited to laboratories and medical congresses – far away from the lives of the people it impacted the most.

The episode below involves the speakers Dr. Kimbley Smith, Head of Research and Development (R&D) at ViiV Healthcare, and Charles Stephens, Executive Director of the Counter Narrative Project (CMP). He is based in Atlanta, Georgia, and is advocating on behalf of black gay, bi and queer men.

Charles talks about what chemsex is and some of the risks involved, while concentrating on pro-sex and pro-pleasure mentalities and ways to combat stigma:

What are the risks associated with chemsex?

Although chemsex provides many with enhanced sexual pleasure, experimentation, social connections, and escapism, it's essential to acknowledge that it may also carry potential risks.

Chemsex is sometimes associated with mental health issues such as depression, anxiety and suicidal risks, which can have a direct impact on accessing HIV prevention services.6 For people living with HIV, these mental health problems may also impact adherence to their antiretrovirals (ARVs).6 Other mental health impacts include psychological effects like hallucinations, paranoia, and psychosis (delusion or disordered speaking and thinking).12,16Taking care of your mental health during chemsex is essential, and understanding the ins and outs of chemsex psychology can make a big difference in how you approach it.

In terms of physical health, other complications include overdose, cardiovascular problems, and damage to the nose and throat from drug use.17,18 An overdose is potentially life-threatening, especially with substances such as GHB, which can lead to difficulty breathing, respiratory arrest, and sometimes death.19,13

It's essential to recognise that individuals involved in chemsex may also face external risks, like the potential involvement of chemsex crime gangs through a phenomenon known as 'cuckooing.20 The impact of chemsex cuckooing is a potential danger to vulnerable individuals in the chemsex scene, such as those battling drug addiction and mental health issues.20 Therefore, it is important for these individuals to be fully aware of all possible dangers so that they can stay safe.

Can chemsex lead to addiction?

Yes, engaging in chemsex can potentially lead to addiction. The misuse of psychoactive substances, or even some prescription drugs (such as opioids and sedatives), can be highly addictive. Frequent chemsex may lead to dependence and the development of substance use disorder.21

Sex itself can be very addictive for some people, so combining sex with highly addictive psychoactive substances acts as a double-edged sword.22 If you or someone you know is struggling with addiction related to chemsex, seek professional help from addiction specialists.


There is an increased chance of HIV transmission for those engaging in chemsex due to several factors:23

  • Drug use can cause people to lose inhibitions during sex, which may interfere with safe sex practices such as using condoms.7
  • Disinhibition can lead to other uninhibited sexual behaviours such as having multiple or anonymous sex partners with an unknown HIV status.11
  • Sexual encounters typically last longer during chemsex, increasing the time for potential transmission.4

Despite the increased chance of HIV transmission, preventative measures such as PrEP can make transmission significantly less likely.1 However, it is very important that it is taken as prescribed, as lowered inhibitions may pose challenges to consistent use, especially if the chemsex session or party lasts several days.4

Harm reduction strategies and chemsex

Using harm reduction strategies and seeking support and guidance can contribute to a safer and healthier experience during chemsex. Such strategies include:

  • Using safer sex practices (consistent condom use, using water-based lubrication, regular testing for STIs and HIV). Use a new condom every time you engage in intercourse with a new sexual partner. If you struggle with the use of condoms, consider PrEP to protect against HIV.24
  • Avoiding the shared use of drug equipment such as needles. For instance, use a new needle for each slam, or consider using needles of different colours for each sexual partner to prevent mixing them.24
  • Taking breaks during extended sessions, as this can aid safer substance use and prevent burnout. Taking breaks facilitates open communication, ensuring that all participants are comfortable, consenting and on the same page.
  • Staying hydrated, as many drugs used during chemsex may induce dehydration which can exacerbate their effects. Breaks, as outlined in the previous point, will help people achieve this.24
  • Being mindful of substance intake to reduce the likelihood of overconsumption. Overdose can be life-threatening. Note down when you have last taken a dose (e.g. of GHB/GBL) or set an alarm on your phone. Sometimes if we are not sure when we took the last dose, we run the risk of taking more too soon, causing accidental overdoses.24
  • Building and maintaining supportive social networks that include friends, healthcare professionals, or community organisations. This can provide emotional support and access to resources for safer practices.


There are support services available that can offer guidance and assistance for individuals involved in chemsex. These can include sexual health clinics, drug treatment centres, counselling services, and community organisations. These organisations are specialised in providing support and harm reduction advice specifically tailored to chemsex-related issues.


  1. CDC. Detailed STD Facts - HIV/AIDS & STDs. Published 2023. Accessed November 30, 2023.
  2. Giorgetti R, Adriano Tagliabracci, Schifano F, Zaami S, Marinelli E, Francesco Paolo Busardò. When “Chems” Meet Sex: A Rising Phenomenon Called “ChemSex.” Current Neuropharmacology. 2017;15(5). doi:
  3. SH:24. Chemsex | SH:24. Published 2023. Accessed November 30, 2023.
  4. McCall H, Adams N, Mason DE, Willis J. What is chemsex and why does it matter? BMJ. Published online November 3, 2015:h5790-h5790. doi:
  5. World. Drugs. Published July 10, 2019. Accessed November 30, 2023.
  6. ViiV Healthcare. THE ViiV HEALTHCARE POSITIVE ACTION FUND. Call for Proposals, Innovator 2023 Harm reduction and HIV prevention, care and treatment for communities who engage in chemsex. Published 2023. Accessed December 4, 2023.
  7. Pufall E, Kall M, Shahmanesh M, et al. Sexualized drug use (“chemsex”) and high-risk sexual behaviours in HIV-positive men who have sex with men. HIV Medicine. 2018;19(4):261-270. doi:
  8. Harm Reduction International. The Global State of Harm Reduction. Regional Overview: Asia. Chemsex in Asia.; 2022.
  9. Cesare Di Feliciantonio, Brown G. Chemsex at home: Homonormative aspirations and the blurring of the private/public space divide. Geoforum. 2023;147:103879-103879. doi:
  10. Whitlock G, Protopapas K, Bernardino JI, et al. Chems4EU: chemsex use and its impacts across four European countries in HIV‐positive men who have sex with men attending HIV services. HIV Medicine. 2021;22(10):944-957. doi:
  11. Ivey K, Bernstein KT, Kirkcaldy RD, et al. Chemsex Drug Use among a National Sample of Sexually Active Men who have Sex with Men, – American Men’s Internet Survey, 2017–2020. Substance Use & Misuse. 2023;58(5):728-734. doi:
  12. Íncera-Fernández D, Gámez-Guadix M, Moreno-Guillén S. Mental Health Symptoms Associated with Sexualized Drug Use (Chemsex) among Men Who Have Sex with Men: A Systematic Review. International Journal of Environmental Research and Public Health. 2021;18(24):13299-13299. doi:
  13. Ma X, Perera S. Safer “chemsex”: GPs’ role in harm reduction for emerging forms of recreational drug use. British Journal of General Practice. 2015;66(642):4-5. doi:
  14. Ahmed AK, Weatherburn P, Reid D, et al. Social norms related to combining drugs and sex (“chemsex”) among gay men in South London. International Journal of Drug Policy. 2016;38:29-35. doi:
  15. Agnew E, McAloney-Kocaman K, Wiseman-Gregg K. Variations in stigma by sexual orientation and substance use: An investigation of double stigma. Journal of Gay & Lesbian Social Services. 2023;35(1). doi:
  16. Lucía Moreno-Gámez, Hernández-Huerta D, Lahera G. Chemsex and Psychosis: A Systematic Review. Behavioral sciences. 2022;12(12):516-516. doi:
  17. Cora von Hammerstein, Joël Billieux. Sharpen the focus on chemsex. Addictive Behaviors. 2024;149:107910-107910. doi:
  18. 56 Dean St. Mephedrone: Chems Support. Published August 12, 2020. Accessed December 4, 2023.
  19. Morse BL, Vijay N, Morris ME. γ-Hydroxybutyrate (GHB)-Induced Respiratory Depression: Combined Receptor-Transporter Inhibition Therapy for Treatment in GHB Overdose. Molecular Pharmacology. 2012;82(2):226-235. doi:
  20. Home Office. From harm to hope: A 10-year drugs plan to cut crime and save lives. GOV.UK. Published December 9, 2021. Accessed November 30, 2023.
  21. Thiago Silva Torres, Leonardo Soares Bastos, Kamel L, et al. Do men who have sex with men who report alcohol and illicit drug use before/during sex (chemsex) present moderate/high risk for substance use disorders? Drug and Alcohol Dependence. 2020;209:107908-107908. doi:
  22. Léo Malandain, Blanc JV, Ferreri F, Thibaut F. Pharmacotherapy of Sexual Addiction. Current Psychiatry Reports. 2020;22(6). doi:
  23. Luis J, Dimitra Panagiotoglou, Greenwald ZR, et al. Chemsex and incidence of sexually transmitted infections among Canadian pre-exposure prophylaxis (PrEP) users in the l’Actuel PrEP Cohort (2013–2020). Sexually Transmitted Infections. 2022;98(8):549-556. doi:
  24. Controlling Chemsex. Chemsex harm reduction information | Controlling Chemsex. Published 2018. Accessed December 4, 2023.

NP-GBL-HVX-COCO-240005 | January 2024

Reporting of side effects

If you get any side effects, talk to your doctor, pharmacist or nurse. This includes any possible side effects not listed in the package leaflet. You can also report side effects directly via the Yellow Card Scheme at or search for MHRA Yellowcard in the Google Play or Apple App store. By reporting side effects, you can help provide more information on the safety of this medicine.

If you are from outside the UK, you can report adverse events to GSK/ViiV by selecting your region and market, here.