Substance
What not to mix with Fentanyl
Opioid
Also calledfent, fentanil, carfentanil, nitazene, nitazenes
Synthetic — potent by micrograms, unevenly mixed
Summary
Fentanyl is checked against 40 other substances — 12 dangerous, 4 unsafe and 6 caution.
Dangerous
12- Fentanyl and AlcoholThe active dose of fentanyl is measured in micrograms, and illicit powder or pressed pills are almost never mixed evenly — two pills from the same…
- Fentanyl and BenzodiazepinesThe single most lethal pairing in current overdose data. Benzodiazepines remove the arousal response you would otherwise rely on to keep breathing…
- Fentanyl and CodeineAdditive respiratory depression, with fentanyl setting the risk. Codeine adds little effect and meaningful danger.
- Fentanyl and DXMCNS depression, difficult breathing, heart issues, hepatoxic, just very unsafe combination all around. Additionally if one takes DXM, their tolerance…
- Fentanyl and GHB / GBLTwo substances with almost no margin between a working dose and an unrousable one, acting on different receptors so neither ceiling helps. Naloxone…
- Fentanyl and KetamineBoth substances bring a risk of vomiting and unconsciousness. If the user falls unconscious while under the influence there is a severe risk of vomit…
- Fentanyl and KratomFentanyl sets the risk here and kratom does nothing to blunt it. Kratom's ceiling protects against kratom, not against a full agonist dosed in…
- Fentanyl and MethadoneMethadone accumulates over days and stays active far longer than it feels active. Fentanyl on top of a methadone dose from yesterday is a common and…
- Fentanyl and MXEThis combination can potentiate the effects of the opioid
- Fentanyl and OpioidsTolerance built on heroin or oxycodone does not translate cleanly to fentanyl, and fentanyl is increasingly what is actually in both. Stacking them…
- Fentanyl and PregabalinGabapentinoids carry an FDA respiratory-depression warning specifically for combination with opioids, and pregabalin appears in a rising share of…
- Fentanyl and TramadolConcomitant use of tramadol increases the seizure risk in individuals taking other opioids. These agents are often individually epileptogenic and may…
Unsafe
4- Fentanyl and BuprenorphineNot an overdose risk so much as a specific and very unpleasant trap. Buprenorphine binds the mu receptor more tightly than fentanyl and has low…
- Fentanyl and CocaineA speedball in current form. The stimulant masks how sedated you are, so you dose again; cocaine then clears in under an hour while fentanyl is still…
- Fentanyl and DiphenhydramineBoth substances are CNS depressants, potentiating each other strongly and unpredictably, raising the chances of memory loss, severe ataxia, and…
- Fentanyl and MethamphetamineSame mechanism as the cocaine pairing but stretched over a much longer stimulant window, so the fentanyl is often redosed repeatedly across it. The…
Caution
6- Fentanyl and AmphetaminesStimulants increase respiration rate, which can allow for a higher dose of opiates normal . If the stimulant wears off first then the opiate may…
- Fentanyl and LithiumNo direct pharmacokinetic interaction, but additive sedation and any dehydration or reduced kidney perfusion can raise lithium levels. Note that…
- Fentanyl and MAOIsCoadministration of monoamine oxidase inhibitors (MAOIs) with certain opioids has been associated with rare reports of severe and fatal adverse…
- Fentanyl and MephedroneStimulants increase respiration rate allowing a higher dose of opiates. If the stimulant wears off first then the opiate may overcome the patient and…
- Fentanyl and Nitrous OxideBoth substances potentiate the ataxia and sedation caused by the other and can lead to unexpected loss of consciousness at high doses. While…
- Fentanyl and PCPPCP can reduce opioid tolerance, increasing the risk of overdose
Low / synergy
1Low / no synergy
17Checking more than one?
This page rates Fentanyl against one substance at a time. Combinations of three or more carry risks that no pair-by-pair list can show — the checker rates every pair at once and flags the whole-mix ones on top.
Open Fentanyl in the checkerOther opioids
All combinations →Educational information only, not medical advice. Absence of a documented interaction is not evidence of safety. Combination data from the TripSit drug combination chart, retrieved 2026-08-20.