Crystal Meth, Yaba, Ketamine and GHB in Chemsex: Risks and Danger Signs
Crystal meth, yaba, ketamine and G carry different dangers. Learn the sexual-health risks, interactions with erection and HIV medicines, overdose signs and when to get emergency help.
Key points
- Stimulants (crystal meth, yaba) strain the heart and can cause stroke and drug-induced psychosis; GHB and ketamine slow breathing and cause loss of consciousness, especially with alcohol.
- Never combine poppers with erection medicines, and boosted HIV medicines can raise levels of some drugs, so tell your doctor honestly.
- Cannot be woken, slow breathing, seizures, chest pain or overheating: call 1669 at once. Stopping regular GHB use needs medical supervision.
This article is part of the series What is chemsex and how to reduce harm. It focuses on the substances I see most often in my clinic: crystal meth ("ice"), yaba, ketamine and G (GHB/GBL). It is written so that you and your friends can recognise danger. It does not explain how to use anything, and it does not judge anyone.
How these substances differ
Broadly, there are two groups. Stimulants, such as crystal meth, yaba and mephedrone, speed up the heart, raise blood pressure and stop you sleeping. Depressants and dissociatives, such as GHB/GBL and ketamine, dull awareness, slow breathing and can make you pass out. Using several at once makes the effects overlap and much harder to predict.
Getting to know each substance and its specific risks
Each substance works differently, so the dangers differ too. This section does not explain how to use anything. It explains what the danger signs are and what you should never do, so that you and your friends are safer.
Methamphetamine: crystal meth ("ice") and yaba
What it is. Methamphetamine is a stimulant. In Thailand, "yaba" is methamphetamine in tablet form, usually mixed with caffeine, while "ice" (ya ice) is the crystal form, which is purer and stronger. In Thailand it is a Category 1 narcotic.
Why it is used for sex. It makes people alert, raises sex drive and confidence, and keeps people going for hours or even days.
Main risks
- Heart and blood vessels. Palpitations, high blood pressure, irregular heartbeat, heart attack, stroke and overheating, even in young people.
- Mental health. Days without sleep, irritability, paranoia and hearing voices. Methamphetamine-induced psychosis becomes more likely with heavier and longer use, and in some people it does not fully go away after stopping.
- Dependence. It is very addictive. Comedowns often bring depression, exhaustion and strong cravings.
- Sexual health. Desire is high but erections can be difficult, so many people add erection medicines, which further strains the heart. Long sessions cause small tears and make condoms more likely to break. Injecting carries a very high risk of HIV and hepatitis C.
- Long-term effects on the body. Tooth decay, skin sores from picking and weight loss.
Reducing harm. If you have heart disease, high blood pressure or a history of psychosis, your risk is much higher than average. Let your body rest and sleep, drink water and eat, don't inject and never share any equipment. If you start to feel paranoid or hear voices, stop and see a doctor.
Ketamine ("K")
What it is. Ketamine is an anaesthetic used in medicine, with a dissociative effect that makes people feel detached from their body. Outside medical use it is a controlled substance and illegal.
Why it is used for sex. It relaxes people and their muscles and reduces pain.
Main risks
- Confusion, being unable to move, or losing consciousness (sometimes called a "K-hole"). This brings a risk of falls, drowning, choking and getting hurt without noticing, because pain is dulled.
- Consent. A person in this state cannot give consent.
- Mixing with alcohol or GHB suppresses breathing further and can lead to vomiting and choking.
- Bladder damage. Frequent or long-term use can cause ketamine-associated cystitis (ketamine uropathy): lower abdominal pain, needing to pass urine often, pain when urinating, leaking, or blood in the urine. In severe cases the bladder shrinks permanently and the kidneys can be affected.
- Severe abdominal pain and bile-duct problems in regular users, plus psychological dependence.
Reducing harm. Don't mix it with other depressants. Stay somewhere safe, away from water and heights. If you start having urinary symptoms, stop and see a doctor early, because many people improve when they stop at an early stage.
GHB / GBL ("G", "gina")
What it is. GHB is a depressant, and GBL is converted into GHB in the body. Both are illegal in Thailand.
Why it is used for sex. It relaxes people, increases desire and lowers inhibitions.
Main risks
- The gap between "feeling it" and "passing out" is very narrow, and the strength varies from one batch to the next. This is why GHB is a common cause of people collapsing at parties.
- Mixing with alcohol, sleeping pills or ketamine can stop breathing and kill.
- Vomiting while unconscious and inhaling it into the lungs.
- Dependence develops quickly. People who use it around the clock and then stop suddenly can have severe withdrawal, with confusion, hallucinations and seizures, which can be fatal. Stopping needs medical supervision.
- Consent. GHB is used to drug people for sexual assault. Putting a substance in someone else's drink is a serious crime.
Reducing harm. Never mix it with alcohol. Don't use alone, and never leave your drink unattended. If you use it every day and want to stop, talk to a doctor before stopping on your own.
Mephedrone (briefly)
Mephedrone ("meow meow", "M-cat") is a synthetic cathinone, a stimulant with effects somewhere between crystal meth and MDMA. Its effects are short, which drives frequent redosing. Risks include a fast heart rate, high blood pressure, overheating, anxiety, paranoia and dependence. In some countries it is injected ("slamming"), which carries a very high risk of HIV and hepatitis C. It is a controlled substance under Thai drug law.
Crystal meth / yaba
Stimulant
- Heart, blood pressure, stroke
- Paranoia, drug-induced psychosis
- Addictive; injecting risks HIV/hep C
Ketamine
"K"
- Confusion, can't move, passing out
- Chronic bladder damage
- With depressants, slowed breathing
GHB / GBL
"G"
- Tiny gap between high and passing out
- With alcohol, breathing can stop
- Severe withdrawal; used for drugging
Mephedrone
Stimulant
- Fast heart rate, overheating
- Short effect, compulsive redosing
With your medicines
- Poppers + erection pills: never
- Boosted HIV meds raise drug levels
Every substance lowers inhibitions, raises HIV/STI risk and makes consent unclear.
Common sexual-health risks
- High desire but difficult erections. Stimulants narrow blood vessels, so many men add erection medicines.
- Long sessions with dulled pain cause small tears, make condoms more likely to break, and raise the risk of HIV, syphilis, gonorrhoea and hepatitis C.
- Forgetting protection: no condom, or missed PrEP doses during multi-day parties.
- Unclear consent when someone is very intoxicated or unconscious.
- An erection lasting more than 4 hours needs hospital care immediately.
Protection includes condoms, lubricant, PrEP, PEP within 72 hours and regular STI testing.
Interactions with erection medicines, poppers and regular medication
Patients ask me this often, and it is something to tell your doctor honestly, because some combinations can be fatal.
Erection medicines (PDE5 inhibitors). Crystal meth and yaba already raise heart rate and blood pressure; adding erection medicines puts even more strain on the heart and raises the risk of a prolonged erection. Poppers with erection medicines can make blood pressure crash, causing fainting or shock, so never combine them. Read poppers: what they are and PDE5 inhibitors.
| What you take | What you should know |
|---|---|
| Oral PrEP (tenofovir/emtricitabine) | No important interactions with these substances are known. The main problem is missed doses during multi-day parties, which weakens protection against HIV. |
| HIV medicines with a booster, such as ritonavir or cobicistat | These block the liver enzymes that clear drugs, so blood levels of MDMA, methamphetamine, ketamine and GHB may be higher than expected. Deaths have been reported. Boosters also raise levels of erection medicines a lot, so doses need adjusting by a doctor. |
| Thailand's main HIV regimen (TLD) | Has no booster and fewer interactions, but missing doses often can let the virus rebound and become resistant. |
| SSRI antidepressants and psychiatric medicines | Combined with MDMA, mephedrone or stimulants, there is a risk of serotonin syndrome or a flare-up of psychiatric symptoms. |
If you take HIV medicines, read about HIV treatment and recommended regimens and ask your doctor whether your regimen contains a booster. A doctor can check interactions for you without judgement. If you often forget PrEP during parties, talk to your doctor about other options, such as injectable PrEP, where suitable.
Overdose signs and when to call 1669
Depressants (GHB/GBL, ketamine, especially mixed with alcohol)
- Cannot be woken, or does not respond when called
- Slow or irregular breathing, loud snoring sounds, or blue or grey lips
- Vomiting while barely conscious
Stimulants (crystal meth, yaba, mephedrone)
- Chest pain or tightness, severe palpitations, or fainting
- Very high body temperature, heavy sweating, confusion or seizures
- Sudden severe headache, weakness on one side of the body, or slurred speech
- Severe paranoia with a risk of harming themselves or others
Other reasons to go to hospital quickly: an erection lasting more than 4 hours, being unable to pass urine or passing a lot of blood, and GHB withdrawal symptoms such as shaking, confusion or hallucinations.
While waiting for the ambulance, put the person in the recovery position on their side and stay with them the whole time. Don't leave them to "sleep it off" alone, don't try to treat them with another substance, and note what was taken and when so you can tell the medical team.
Don't treat it with another substance, and never leave someone to 'sleep it off' alone.
Cutting down or stopping safely
Some substances are not safe to stop suddenly on your own, especially GHB used regularly, where sudden withdrawal can cause seizures and can be fatal, so stopping needs medical supervision. With crystal meth and yaba, stopping often brings low mood, exhaustion and cravings; if you have thoughts of harming yourself, call 1323 (24 hours; Thai language, ask for English support). If you use ketamine and develop urinary symptoms, stop and see a doctor early.
For initial advice, call the 1165 drug-treatment hotline (Thai language) or contact a treatment clinic at a public hospital. All the help options are listed in chemsex: overview and where to get help.
How Dr. Kris can help
At Dr. Kris Clinic we provide non-judgmental, confidential care: checking interactions between your medicines and substances, planning HIV prevention with PrEP/PEP, STI testing, help with erections and confidence after cutting down, and referral to a psychiatrist, treatment service or urologist when needed. If you also use cannabis, read cannabis and sex. Consultations are available at the clinic and online, including in English.
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HIV risk, or want to start PrEP?
Consult in clinic or online. After a recent exposure, PEP works best the sooner it starts — within 72 hours.
Every medicine and service requires a doctor's assessment first.
Frequently asked questions
What should I do if a friend passes out after using GHB?
Call 1669 immediately, put them on their side, watch their breathing, don't give them anything to eat or drink, don't leave them alone, and tell the medical team what they took.
I take HIV medicines. Is using drugs more dangerous for me?
It depends on your regimen. Regimens with ritonavir or cobicistat can push levels of MDMA, crystal meth, ketamine or GHB dangerously high, while TLD has fewer interactions. Tell your doctor honestly so they can check for you.
I use ketamine and need to pee often and it hurts. Are these linked?
They may be signs of ketamine-associated bladder damage. Stop using and see a doctor soon, because many people improve when they stop at an early stage.
Crystal meth makes it hard to get an erection. Can I use erection pills?
Using them on your own isn't recommended, because they add strain on the heart and raise the risk of a prolonged erection, and they must never be combined with poppers. If you have erection problems, talk to a doctor openly so both the drug use and the sexual health side can be looked after together.
อ่านบทความนี้เป็นภาษาไทย
ยาไอซ์ ยาบ้า เคตามีน และ G กับเซ็กซ์: ความเสี่ยงและสัญญาณอันตราย →
References
- European Union Drugs Agency (EUDA/EMCDDA). European Drug Report 2024: GHB and drug use in sexual contexts.
- Harrington RD, Woodward JA, Hooton TM, Horn JR. Life-threatening interactions between HIV-1 protease inhibitors and the illicit drugs MDMA and gamma-hydroxybutyrate. Arch Intern Med. 1999;159(18):2221-2224.
- University of Liverpool. HIV Drug Interactions Checker (hiv-druginteractions.org): recreational drugs. Accessed 2026.
- Shahani R, Streutker C, Dickson B, Stewart RJ. Ketamine-associated ulcerative cystitis: a new clinical entity. Urology. 2007;69(5):810-812.
- McKetin R, Lubman DI, Baker AL, Dawe S, Ali RL. Dose-related psychotic symptoms in chronic methamphetamine users. JAMA Psychiatry. 2013;70(3):319-324.
- ประมวลกฎหมายยาเสพติด พ.ศ. 2564
- Darke S, Kaye S, McKetin R, Duflou J. Major physical and psychological harms of methamphetamine use. Drug Alcohol Rev. 2008;27(3):253-262.
This article is for education and does not replace diagnosis or treatment by a doctor. If you have symptoms or concerns, please see a doctor.
