Methamphetamine (crystal, tina)
Methamphetamine is a central nervous system stimulant with effects that may last 6 to 24 hours or longer. It may reduce ART adherence and has relevant interactions with antidepressants and erection medicines. The risks of psychosis, sleep deprivation, and redosing are especially important in chemsex contexts.
What is it?
Methamphetamine (also known as crystal, tina, ice, or speed) is a powerful central nervous system stimulant. It may appear as white powder, crystals (crystal/tina), or pills. Its effects may last 6 to 24 hours or more depending on dose, route, and the person, which distinguishes it from cocaine and other shorter-acting stimulants.
How is it used?
| Route | Onset | Notes |
|---|---|---|
| Snorted | 10-20 min | Progressive damage to the nasal lining |
| Smoked | Seconds | Very fast onset; may lead to redosing |
| Inhaled / vaporised | Seconds | Similar to smoking |
| Injected | Seconds | Most intense effect; greater risk of infections and overdose |
| Oral | 30-60 min | Slower onset and longer-lasting effect |
The fast onset of inhaled, smoked, and injected use may lead to unintentional redosing before the previous dose has passed.
How does it work?
Methamphetamine causes a massive release of dopamine, noradrenaline, and serotonin in the brain, which may produce:
- More energy, euphoria, and concentration
- Increased confidence and sociability
- Less need for sleep and appetite
- Faster pulse, higher blood pressure, and higher body temperature
Effects may last between 6 and 24 hours or more, which may lead to prolonged sleep deprivation.
Specific risks
1. Substance-induced psychosis
With high doses, prolonged use, lack of sleep, or in more sensitive people, it may cause:
- Paranoia and intense distrust
- Persecutory ideas
- Hallucinations (seeing or hearing things that are not there)
- Strange or disorganised behaviour
2. Sleep deprivation
Methamphetamine may keep you awake for many hours or even days, causing:
- Extreme exhaustion and irritability
- Anxiety and sadness
- Greater risk of psychosis
- Reduced decision-making ability
3. Redosing
The initial intense effect may lead to taking more before the previous dose has worn off. It is recommended to wait at least 1-2 hours and start with low doses. Risks include overdose, hyperthermia, anxiety, paranoia or psychosis, and heart problems.
4. Prolonged sex (chemsex)
Methamphetamine may increase sexual desire and endurance, but it may also cause:
- Dehydration and exhaustion
- Injuries, irritation, or bleeding
- Reduced ability to make decisions and set limits
- Greater risk of STIs and HIV
Interactions with medicines
| Medicine / Group | Risk level | Effect on adherence and health |
|---|---|---|
| ART (antiretroviral treatment) | Moderate | It may reduce adherence because of missed doses, disorganisation, or intense use. Do not stop ART. Use reminders and keep regular follow-up. |
| PrEP (TDF/FTC, TAF/FTC) | Low | Adherence may drop because of missed doses. There is no major pharmacological interaction. Set reminders. PrEP protects when taken consistently. |
| PEP (TDF/FTC + raltegravir or dolutegravir) | Moderate | It may reduce adherence because of missed doses. Nausea and discomfort may feel worse. Complete the 28 days. Ask for help if adverse effects are intense. |
| Hormones (affirming therapy) | Low | Adherence may drop because of missed doses. There is no major pharmacological interaction. Continue your hormones and follow-up. |
| Erection medicines (sildenafil, tadalafil) | Moderate | Greater risk of tachycardia, high blood pressure, and palpitations. Use low doses. Do not combine with additional stimulants. |
| SSRI / SNRI antidepressants | Moderate-High | Risk of serotonin syndrome (confusion, agitation, fever, tremors, rigidity). Do not combine without medical supervision. Always ask first. |
Harm reduction
- Less is more: use low doses and wait before redosing
- Wait at least 1-2 hours before taking more
- Sleeping, hydrating, and eating improve well-being and reduce risk
- Use in safe spaces and with trusted people
- Maintain ART adherence: use reminders and do not skip doses
- Tell your healthcare team about methamphetamine use
- Take care of sexual health: use condoms and lube, and keep in mind the higher STI risk
Warning signs
- Chest pain, shortness of breath, fainting, or strong palpitations
- Very high body temperature, excessive sweating, or confusion
- Intense anxiety, paranoia, or thoughts of harming yourself or others
- Seizures or loss of consciousness
If any of these happen, seek medical care immediately.
When should you seek medical care?
- Chest pain or trouble breathing
- Loss of consciousness or seizures
- Very high body temperature that does not come down
- Intense paranoia or behaviours that put safety at risk
- Thoughts of self-harm
What does the evidence say?
Methamphetamine has significant potential to reduce ART adherence, especially during periods of intense use or prolonged chemsex. Direct pharmacological interactions with most modern antiretrovirals (integrase inhibitors, tenofovir) are limited, but the strain on the cardiovascular system and the risk of serotonin syndrome with serotonergic antidepressants are documented. Use in chemsex settings increases the risk of STIs and HIV regardless of serostatus. Mental health care and adherence to treatment are central to well-being for people who use methamphetamine.