Ketamine

Ketamine is not part of the chemsex definition but its a stubborn outlier, part of the landscape, falling in and out of popularity. This is why we’ve included it.

Ketamine is used because of how it changes the way people feel in their body and mind. It can create a sense of distance from stress, pain, or self-doubt, and help people feel more relaxed or open in the moment. For some, it softens emotions, quietens worries, and makes touch, music, or sex feel different or less pressured. Its effects are short-lived, which can feel manageable and intentional.

It’s used alongside other drugs, or during sex, to stay present without feeling overwhelmed. However, like any drug, it carries risks, especially with frequent use, but its appeal lies in how it can temporarily make difficult feelings easier to sit with.

From the late 1990s onwards, ketamine was already present in queer club nights, after-hours parties, and warehouse spaces. For some men, ketamine offered effects that felt compatible with sex-positive spaces: lowering social anxiety, easing self-consciousness, and changing how the body and intimacy were experienced. Its shorter duration and lower intensity compared with some stimulants made it easy to use casually, socially, or alongside sex without committing to long sessions.

As London’s gay scenes evolved, ketamine was sometimes seen as distinct from stimulant-led chemsex, and in some circles became associated with alternative, creative, or post-club cultures. Its availability, affordability, and ease of use further supported its uptake.

Why ketamine is suddenly so popular | Asap SCIENCE | 27 Mar 2025 | 6m 29s 

K-hole
Can happen after taking a high dose of ketamine. Described as feeling deeply disconnected from their body, surroundings, and sense of self. Movement and speech can become very difficult or impossible for a period of time. Time may feel distorted, and some people experience vivid inner imagery or a sense of “leaving” their body. For some, a K-hole feels calm or introspective. For others, it can be frightening, confusing, or overwhelming, especially if unexpected. Because awareness and coordination are reduced, there is a real risk of injury, choking, or vulnerability, particularly if mixed with alcohol or other drugs.

K bladder
Ketamine irritates the lining of the bladder. Over time, this can lead to inflammation, scarring, and reduced bladder capacity. People may need to urinate very often, feel urgent pain, or pass blood. Some describe it as feeling like a constant urinary infection that doesn’t clear. Early signs can appear surprisingly quickly, sometimes within months of frequent use. If ketamine use continues, the damage can become severe and, in some cases, permanent, occasionally requiring surgery or long-term catheter use, not a great look at sex parties. Harm to the bladder is dose and frequency related, often underestimated, and improves only if ketamine use is reduced or stopped early.

K, the ‘horse drug’
Ketamine became known among gay men as the “horse drug” because of its long-standing veterinary association, widely used by vets since the 1960s, particularly for sedating large animals such as horses. For gay men the label has served a few functions: to signal that the drug was pharma legitimate, distinguish it from street-made substances, and add a layer of dark humour and insider knowledge.

Ketamine’s use in treating depression
This reflects limits of conventional antidepressants and advances in neuroscience. At low, controlled doses, ketamine can produce rapid antidepressant effects, sometimes within hours, by acting on the glutamate system rather than serotonin. It appears to increase neural plasticity and disrupt rigid negative thought patterns. This has made it particularly relevant for treatment-resistant depression and acute suicidal ideation, under strict clinical supervision.

Ketamine harms are complicated
Risks increase with frequent use, higher doses, and regular redosing. Ketamine’s harms are often slow, cumulative, and underestimated. Many people feel fine until damage, especially to the bladder, has already begun.

Physical harms

• Bladder and urinary damage: pain, urgency, bleeding, infections, and in severe cases permanent damage requiring surgery
• Kidney problems linked to ongoing bladder inflammation
• Liver irritation with heavy or prolonged use
• Numbness to pain increases risk of injury, accidents, and unnoticed harm
• Overdose risk, especially when mixed with alcohol, benzodiazepines, or opioids.

Mental and emotional harms

• Memory and concentration problems, particularly with regular use
• Low mood, anxiety, or emotional flatness between sessions
• Psychological dependence: using ketamine to cope, switch off, or feel “normal”.

Sexual and social harms

• Reduced awareness of consent, boundaries, and risk
• Higher risk of sexual assault or exploitation, especially in group or party settings
• Relationship strain and isolation when use becomes central

Dependence and addiction

• Rapid tolerance leading to frequent redosing
• Escalation from occasional to daily use can happen quickly

A brief history

• 1962: Ketamine was synthesised by Parke-Davis as a safer alternative to phencyclidine (PCP). It was designed to produce “dissociative anaesthesia” with preserved airway reflexes.
• 1970s: Widely adopted as an anaesthetic, particularly in the Vietnam War, and in paediatrics, emergency medicine, and veterinary practice.
• 1980s: Routine medical and veterinary use but appears sporadically in club and counterculture settings.
• 1990s: Gains visibility in rave and club scenes in the US and Europe. Snorted and injected and associated with dissociation rather than stimulation. However, concerns about bladder and cognitive effects begin to surface.
• 2000s: Still widely used in veterinary medicine and emergency care coupled with wider recreational use across Europe and Asia. Increased recognition of ketamine-induced cystitis and dependence patterns. Drug scheduling tightens: UK Class C (2006).
• 2010s: Evidence accumulates for rapid-acting antidepressant effects at low doses, and ketamine clinics emerge (IV infusions for treatment-resistant depression). Recreational use expands including sexualised drug use, and chemsex. UK reclassifies ketamine to Class B (2014).
• 2020s: Esketamine (Spravato) approved for treatment-resistant depression under strict controls, and ongoing research into PTSD, suicidality, and chronic pain. Recreational use continues, with clearer evidence of bladder damage, tolerance, and psychological dependence.

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