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Death may occur when promethazine is combined with other depressants, such as opioids, benzodiazepines, barbiturates, thienodiazepines or other GABAergic substances like alcohol.[1]

Additionally, promethazine is an anticholinergic, and at high doses it may cause delirium and extremely unpleasant if not dangerous experiences. Please be extremely careful when trying this pharmaceutical and use responsible use practices such as always having a tripsitter when using promethazine, especially at high doses.

Summary sheet: Promethazine
Chemical Nomenclature
Common names Phenergan, Lergigan
Substitutive name Promethazine
Systematic name N,N,α-trimethyl-10H-phenothiazine-10-ethanamine
Class Membership
Psychoactive class Deliriant / Depressant
Chemical class Phenothiazine
Routes of Administration

WARNING: Always start with lower doses due to differences between individual body weight, tolerance, metabolism, and personal sensitivity. See responsible use section.

Threshold 5 - 12.5 mg
Light 12.5 - 25 mg
Common 25 - 50 mg
Strong 50 - 100 mg
Heavy 100 mg +
Total 4 - 6 hours
Onset 30 - 60 minutes
Come up 20 - 60 minutes
Peak 1 - 2 hours
Offset 3 - 5 hours
After effects 12 hours

DISCLAIMER: PW's dosage information is gathered from users and resources for educational purposes only. It is not a recommendation and should be verified with other sources for accuracy.


Promethazine (commonly sold as Phenergan or Lergigan) is a depressant substance of the phenothiazine class. Alongside codeine, it is popularly known as one of the active two ingredients in "lean". It acts as an antihistamine.

Promethazine was developed in the mid-1940s by French chemists.[2] Today, it is available in many countries under many brand names.

Subjective effects include muscle relaxation, nausea suppression, and strong sedation. It also reduces motion sickness and has anticholinergic properties.

Promethazine has been shown to have quality hypnotic effects and is sometimes used for this purpose.[3]

It is highly advised to use harm reduction practices if using this substance.

History and culture

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Promethazine was developed in the mid-1940s when a team of scientists from Rhône-Poulenc laboratories was able to synthesize it from phenothiazine and a diamine side chain of diphenhydramine.[2] It was previously used as an antipsychotic, although it is generally not administered for this purpose now. It has approximately 1/10 of the antipsychotic strength of chlorpromazine.

It became popular among the Houston rap and hip-hop scene in around 1990[4], and the trend resurfaced in around 2015 to 2016. Often, it was combined with the opiate drug codeine in a preparation called "lean." Lean usually consists of ice, Sprite or a citrus soda, the promethazine/codeine cough syrup, and occasionally jolly ranchers for enhanced flavor.



This chemistry section is incomplete.

You can help by adding to it.

Promethazine is a phenothiazine-based compound.


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This pharmacology section is incomplete.

You can help by adding to it.

Promethazine is a direct antagonist of histamine H1 receptors, whereas diphenhydramine is an inverse agonist. It is also an antagonist of muscarinic acetylcholine receptors, which is likely the cause of sedation and delirium that occurs with higher doses. It blocks dopaminergic D2 receptors, but weakly.[citation needed]

Subjective effects

Disclaimer: The effects listed below cite the Subjective Effect Index (SEI), an open research literature based on anecdotal user reports and the personal analyses of PsychonautWiki contributors. As a result, they should be viewed with a healthy degree of skepticism.

It is also worth noting that these effects will not necessarily occur in a predictable or reliable manner, although higher doses are more liable to induce the full spectrum of effects. Likewise, adverse effects become increasingly likely with higher doses and may include addiction, severe injury, or death ☠.

Physical effects

Cognitive effects

Visual effects

After effects
Aftereffects (3).svg

Experience reports

Anecdotal reports which describe the effects of this compound within our experience index include:

Additional experience reports can be found here:

Toxicity and harm potential


This toxicity and harm potential section is a stub.

As a result, it may contain incomplete or even dangerously wrong information! You can help by expanding upon or correcting it.
Note: Always conduct independent research and use harm reduction practices if using this substance.

It is strongly recommended that one use harm reduction practices when using this substance.

Lethal dosage

The lowest published toxic dose of promethazine in humans (oral) is 3.5 mg/kg. This means that a person weighing 70 kg can show signs of toxicity at 245 mg. The LD50 of promethazine in mice (oral) is 255 mg/kg. If applied to humans, this suggests that 50% of people weighing 70 kg would die after consuming 17.85 grams of promethazine. [6]

Tolerance and addiction potential

Promethazine is not addictive.

Dangerous interactions


This dangerous interactions section is a stub.

As such, it may contain incomplete or invalid information. You can help by expanding upon or correcting it.

Warning: Many psychoactive substances that are reasonably safe to use on their own can suddenly become dangerous and even life-threatening when combined with certain other substances. The following list provides some known dangerous interactions (although it is not guaranteed to include all of them).

Always conduct independent research (e.g. Google, DuckDuckGo, PubMed) to ensure that a combination of two or more substances is safe to consume. Some of the listed interactions have been sourced from TripSit. Promethazine, because of its extensive pharmacology, has many interactions. According to the interactions checker on, promethazine is known to interact with over 1000 other prescription and OTC drugs.

  • Depressants (1,4-Butanediol, 2-methyl-2-butanol, alcohol, barbiturates, GHB/GBL, methaqualone, opioids) - This combination can result in dangerous or even fatal levels of respiratory depression. These substances potentiate the muscle relaxation, sedation and amnesia caused by one another and can lead to unexpected loss of consciousness at high doses. There is also an increased risk of vomiting during unconsciousness and death from the resulting suffocation. If this occurs, users should try to fall asleep in the recovery position or have a friend move them into it.
  • Anti-dopaminergics - Because promethazine also blocks dopamine receptors, other drugs and substances that do this will increase the chances of developing acute or tardive dyskinesia, neuroleptic malignant syndrome, or parkinsonism.[citation needed]
  • Anticholinergics - Promethazine with anticholinergics (or antimuscarinics) can cause increased blocking of acetylcholine, being potentially dangerous with cardiovascular effects as well as delirium.[citation needed]
  • Stimulants - Due to promethazine's excitatory cardiac effect, combining it with stimulants poses a risk of an abnormal heart rhythm, severe tachycardia, or a heart attack as well as other cardiovascular events.

Legal status

  • Germany: Promethazine is available through a prescription.[citation needed]
  • United States: Promethazine is available through a prescription.[7]

See also

External links



  1. Risks of Combining Depressants. TripSit 
  2. 2.0 2.1 Li, J. J. (2006). Laughing gas, Viagra, and Lipitor: the human stories behind the drugs we use. Oxford University Press. ISBN 9780195300994. 
  3. Adam, K., Oswald, I. (December 1986). "The hypnotic effects of an antihistamine: promethazine". British Journal of Clinical Pharmacology. 22 (6): 715–717. doi:10.1111/j.1365-2125.1986.tb02962.x. ISSN 0306-5251. 
  4. Palmer, T. (2005). Country fried soul: adventures in dirty south hip hop. Backbeat. ISBN 9780879308575. 
  5. 5.0 5.1 Tsay, M. E., Procopio, G., Anderson, B. D., Klein-Schwartz, W. (June 2015). "Abuse and Intentional Misuse of Promethazine Reported to US Poison Centers: 2002 to 2012". Journal of Addiction Medicine. 9 (3): 233–237. doi:10.1097/ADM.0000000000000124. ISSN 1935-3227. 
  7. FDA. Promethazine Monograph.