Addictions

Frequent interactions in a chemsex context: safety guidelines

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Man holding two pills, one blue and one red, near his face.
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Dr Edouard Bougueret

•

Man holding two pills, one blue and one red, near his face.
Male profile picture

Dr Edouard Bougueret

•

PDE5-i, poppers, GHB, stimulants: this summary sheet helps structure a harm reduction discourse in consultation, without dramatization, with concrete indicators and warning signs.

1) General principles (to communicate to patients)

  • In chemsex, the risk often comes from mixes + duration (fatigue, dehydration, redoses).

  • Avoid stacking depressants (GHB/GBL + alcohol/benzodiazepines/opioids/ketamine): this is when loss of consciousness and respiratory distress occur.

  • Buddy system : if possible, do not consume alone; establish "check-ins".

  • In case of ARV/PrEP/psychiatric treatments: think interactions (CYP, sedation, QT, etc.) and check a dedicated resource.

2) Frequent interactions: reference table (HR)

Association (frequent)

Why it poses a problem

Main risks

HR Benchmarks (useful phrases)

PDE5-i (sildenafil/tadalafil) + poppers (nitrites)

Addition of vasodilatory effects →
blood pressure drop

dizziness, syncope, palpitations, chest pain

“One or the other, never both.” Delay without poppers: sildenafil 24 h, tadalafil 48 h.

GHB/GBL + alcohol

Increased respiratory depression and sedation

loss of consciousness, vomiting + inhalation, respiratory arrest

“GHB = zero alcohol.” 
(Even "one drink" increases the risk.)

GHB/GBL + benzodiazepines / opioids

Summation of CNS depressants

coma, respiratory distress

“No benzos/opioids with G.” 
If anxiety/comedown: prioritize non-medicinal measures; if medication, medical advice.

GHB/GBL + ketamine

Sedation + coordination issues + confusion

falls, amnesia, coma

“Avoid the G + K duo.” 
If already taken: close monitoring, recovery position if sleepy.

Stimulants (meth/cocaine/cathinones)
+ other stimulants

Cardiovascular load + hyperthermia + agitation

tachycardia, high blood pressure, chest pain, anxiety attack, overheating

“Avoid stacking stimulants.” 
Breaks, small frequent sips of water, cooling down, sleeping as soon as possible.

Stimulants + GHB/GBL
(the “yo-yo”)

Alternating “up/down” → redoses and loss of bearings

GHB overdose, confusion, risky behaviors

“G to ‘come down’ is a redose trap.” 
Set alarms, space it out, do not try to "catch up".

Cathinones/MDMA + serotonergic antidepressants (SSRIs/SNRIs) / MAOIs

Risk of serotonin syndrome
(especially with polydrug use)

agitation, tremors, hyperthermia, confusion

“If symptoms (fever, rigidity, confusion) = emergency.” 
Increased caution with serotonergic treatment.

Boosted ARVs (ritonavir/cobicistat)
+ PDE5-i / certain chems

Enzymatic inhibition
→ ↑ levels of certain substances

exaggerated effects, hypotension, dizziness, overdose

Check systematically. Example: with ritonavir, sildenafil must be strongly reduced (Liverpool guidelines).

Practical note (consultation) :
if the patient does not know the exact molecules (e.g., “poppers”, “3-MMC”, “critical”), start from the effects (stimulant vs depressant) and the mixes.

3) Warning signs: when it is URGENT (15 / 112)

  • Drowsiness impossible to wake up from, slow/irregular breathing, bluish lips

  • Seizures

  • Chest pain, severe malaise, palpitations + malaise

  • Hyperthermia, confusion, extreme agitation (risk of heat stroke / serotonin syndrome)

  • Suicidal thoughts, delirium, threatening hallucinations

4) Mini-script: “interaction” questions

  1. “What is planned this weekend: stimulants, G, poppers, others?”

  2. “Are you taking any medications ? (ARVs/PrEP, anxiolytics, antidepressants, ADHD, beta-blockers...)”

  3. “Is there any G + alcohol or G + benzos involved?”

  4. “Poppers + erection pills ?”

  5. “Have you ever had a blackout / passed out ?”

  6. “Will you be with someone who can check on you / call if needed?”

5) “Reflex” resource (professionals)

  • ARV ↔ substances / PDE5-i interactions : Liverpool HIV Drug Interactions (checker) Liverpool HIV Interactions

  • General public prevention messages on ARVs and recreational drugs (useful for psychoeducation) aidsmap.com


PDE5-i, poppers, GHB, stimulants: this summary sheet helps structure a harm reduction discourse in consultation, without dramatization, with concrete indicators and warning signs.

1) General principles (to communicate to patients)

  • In chemsex, the risk often comes from mixes + duration (fatigue, dehydration, redoses).

  • Avoid stacking depressants (GHB/GBL + alcohol/benzodiazepines/opioids/ketamine): this is when loss of consciousness and respiratory distress occur.

  • Buddy system : if possible, do not consume alone; establish "check-ins".

  • In case of ARV/PrEP/psychiatric treatments: think interactions (CYP, sedation, QT, etc.) and check a dedicated resource.

2) Frequent interactions: reference table (HR)

Association (frequent)

Why it poses a problem

Main risks

HR Benchmarks (useful phrases)

PDE5-i (sildenafil/tadalafil) + poppers (nitrites)

Addition of vasodilatory effects →
blood pressure drop

dizziness, syncope, palpitations, chest pain

“One or the other, never both.” Delay without poppers: sildenafil 24 h, tadalafil 48 h.

GHB/GBL + alcohol

Increased respiratory depression and sedation

loss of consciousness, vomiting + inhalation, respiratory arrest

“GHB = zero alcohol.” 
(Even "one drink" increases the risk.)

GHB/GBL + benzodiazepines / opioids

Summation of CNS depressants

coma, respiratory distress

“No benzos/opioids with G.” 
If anxiety/comedown: prioritize non-medicinal measures; if medication, medical advice.

GHB/GBL + ketamine

Sedation + coordination issues + confusion

falls, amnesia, coma

“Avoid the G + K duo.” 
If already taken: close monitoring, recovery position if sleepy.

Stimulants (meth/cocaine/cathinones)
+ other stimulants

Cardiovascular load + hyperthermia + agitation

tachycardia, high blood pressure, chest pain, anxiety attack, overheating

“Avoid stacking stimulants.” 
Breaks, small frequent sips of water, cooling down, sleeping as soon as possible.

Stimulants + GHB/GBL
(the “yo-yo”)

Alternating “up/down” → redoses and loss of bearings

GHB overdose, confusion, risky behaviors

“G to ‘come down’ is a redose trap.” 
Set alarms, space it out, do not try to "catch up".

Cathinones/MDMA + serotonergic antidepressants (SSRIs/SNRIs) / MAOIs

Risk of serotonin syndrome
(especially with polydrug use)

agitation, tremors, hyperthermia, confusion

“If symptoms (fever, rigidity, confusion) = emergency.” 
Increased caution with serotonergic treatment.

Boosted ARVs (ritonavir/cobicistat)
+ PDE5-i / certain chems

Enzymatic inhibition
→ ↑ levels of certain substances

exaggerated effects, hypotension, dizziness, overdose

Check systematically. Example: with ritonavir, sildenafil must be strongly reduced (Liverpool guidelines).

Practical note (consultation) :
if the patient does not know the exact molecules (e.g., “poppers”, “3-MMC”, “critical”), start from the effects (stimulant vs depressant) and the mixes.

3) Warning signs: when it is URGENT (15 / 112)

  • Drowsiness impossible to wake up from, slow/irregular breathing, bluish lips

  • Seizures

  • Chest pain, severe malaise, palpitations + malaise

  • Hyperthermia, confusion, extreme agitation (risk of heat stroke / serotonin syndrome)

  • Suicidal thoughts, delirium, threatening hallucinations

4) Mini-script: “interaction” questions

  1. “What is planned this weekend: stimulants, G, poppers, others?”

  2. “Are you taking any medications ? (ARVs/PrEP, anxiolytics, antidepressants, ADHD, beta-blockers...)”

  3. “Is there any G + alcohol or G + benzos involved?”

  4. “Poppers + erection pills ?”

  5. “Have you ever had a blackout / passed out ?”

  6. “Will you be with someone who can check on you / call if needed?”

5) “Reflex” resource (professionals)

  • ARV ↔ substances / PDE5-i interactions : Liverpool HIV Drug Interactions (checker) Liverpool HIV Interactions

  • General public prevention messages on ARVs and recreational drugs (useful for psychoeducation) aidsmap.com


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