Chemical Name:


Street Names:

Tylenol PM, Advil PM, Aleve PM, Benadryl


40 - 60%





Diphenhydramine Dosage




25 mg

100 - 200 mg

200 - 500 mg




500 - 700 mg

700+ mg

1250 - 3000 mg


Remember: Always start with lower dosages! Differences in metabolism, tolerance, sensitivity, and neurochemistry can lead to stronger than expected effects, and even death.

Diphenhydramine Duration


Come up


30 - 90 Minutes

45 - 90 Minutes

1 - 4 Hours


After effects


2 - 6 Hours

24+ Hours

3 - 10 Hours


This substance interacts with:





These interactions may lead to an unpleasant experiences due to substances potentiating each other unpredictably, and/or may be potentially fatal.


Diphenhydramine (Abbreviated as DPH, most common brand name is Benadryl, though other brands of allergy medication also contain this drug) is an antihistamine medication frequently found over the counter to treat allergies and motion sickness. In addition to its use as a medicine, diphenhydramine has found a niche use as a recreational drug due to its powerful hallucinogenic and deliriant effects at high dosages. Before using diphenhydramine, one should know all of the potential negative effects of use, as it is known for causing negative experiences.

Harm reduction

While there is no truly safe way to take diphenhydramine, it is still very important to apply harm reduction practices beforehand (particularly set and setting). If you or anyone you know is planning to trip on diphenhydramine, they should be in a positive mood before going into the experience (set). If one has experienced any major negative event in life, it is not advised to trip on diphenhydramine. The other most important factor is one's surroundings (setting), anyone who is taking this substance should be comfortable with their environment and any people around them. Any slight fear can be amplified during a trip, so if the person tripping is somewhere where they don't feel safe or with people they don't know/trust, then paranoia can quickly build-up.

It is advisable to have a trip sitter while tripping on diphenhydramine, as it can significantly impair one's perception of reality and the ability to care for themselves.

It is recommended to take low doses and avoid redosing, particularly if it is one's first time on this substance.

It's advisable to urinate before dosing since Diphenhydramine is known to cause urinary retention, so urinating during the experience is a very difficult undertaking, and one should make sure they have urinated before the experience.

Avoid tripping on diphenhydramine if you suffer from glaucoma, any cardiac/heart problems, memory problems or allergies to the drug. Stimulant substances should not be combined with diphenhydramine due to their effects on heart rate and blood pressure stacking on top of diphenhydramine's. Blurred vision might persist for a couple of days on high dosages (400-700 mg+), so avoid driving or using any heavy machinery. Make sure the area you're in is clean, any sharp objects must be taken away because you may hurt yourself in confusion. Anything poisonous that seems drinkable should also be taken out of the way as well.

Make sure what you take only contains diphenhydramine. Medications such as Advil PM, Tylenol PM, Aleve PM, etc should NOT be taken for Diphenhydramine trips since they contain other ingredients such as Acetaminophen or Ibuprofen, which can greatly increase risk of organ failure.

Do not combine large dosages of Diphenhydramine with depressant substances due to the risk of respiratory depression.

Do NOT combine diphenhydramine with a MAOI (Monoamine Oxidase Inhibitor). The MAOI will extend diphenhydramine's effects for up to 48 hours.


  • Choline: helps counteract some negative effects induced by Diphenhydramine

  • Huperzine A: like choline, it helps counteract some negative effects, and may prevent some brain damage associated with anticholinerics such as Diphenhydramine.

  • Aspirin: helps with vasoconstriction induced by Diphenhydramine.

  • Ibuprofen: might help with Diphenhydramine induced headaches.

  • DXM: please use this one with caution since it can amplify the trip considerably. However, low dosages may help mitigate some negative effects cause by Diphenhydramine.

Addiction potential

While most don't find the experience of high dosages of diphenhydramine enjoyable, some individuals might take a liking for the deliriant effects of it. diphenhydramine is not addictive, but it might produce some cravings even if the experience wasn't positive. It is not advised to binge on diphenhydramine, because it has neurotoxic effects that will be worsened with heavy or repeated dosing. Diphenhydramine is linked to the development of Alzheimer's disease & Dementia.

Trip Sitting Advice

If you're trip-sitting someone who is having a negative experience on diphenhydramine, first recognize that their perception of reality is skewed. Try your best to remind and prove to them that you're real, as during a state of delirium the person tripping might have trouble differentiating from what is real and what is not. If you're someone they trust a lot, take a gentle approach to the situation, make sure to remind them that they're ok and that they have ingested a drug (you may need to remind them multiple times, due to the memory problems presented by diphenhydramine).

Let them know you're there for them, and that it will all be over soon. If the person tripping starts getting aggressive, attempts to calm them down fail, or they start having a seizure/heart attack, it is imperative that you contact 911 without a second thought as their life or others could be in danger.


As a competitive antagonist of the muscarinic acetylcholine receptors, users may experience extreme drowsiness, restless legs syndrome, rapid breathing, skin flushing, fatigue, confusion, cottonmouth, urinary retention, short-term memory loss, euphoria, dysphoria, increased or decreased sexual arousal, music enhancement, impending feelings of doom, a feeling of heaviness and realistic "true" hallucinations often associated with delirium. In a state of delirium, users experience fully defined visual and auditory hallucinations which they cannot easily differentiate from reality. Remember, delirium is basically psychosis.

Unlike conventional hallucinogens, Diphenhydramine's hallucinations blend in with reality, to the point where they often forget they have taken a drug. Extreme impairment is also present, for instance, walking has been described to be "drunk in the middle of a nightmare and every step hurts beyond belief". Some users (especially males) experience increased sexual stimulation at sub-deliriant doses of Diphenhydramine, however, at common (deliriant) dosages, erectile dysfunction is common.

Only an extremely small minority of users report liking this substance, and an unknown portion of these are reported to use it as a form of chemical self-harm. Effects are generally perceived to be extremely uncomfortable, unsettling, and downright frightening. Some people even claim to have legitimate trauma as a result of experiences with this substance. This, coupled with it's disproportionately high toxicity, makes this a poor substance for recreational use.


Diphenhydramine is a potent antagonist of the H1 (histamine 1) receptors in the body and inside the brain. Due to it's ability to closs the blood-brain barrier, this is the cause of it's sedating effects, which aren't found in antihistamines like fexofenadine and cetirizine, which can't cross. However, it's toxicity and "recreational" effects are the result of antagonism of a set of receptors called the muscarinic acetylcholine receptors (mAChRs). Acetylcholine, their primary endogenous ligand, is an agonist, and is responsible for many aspects of memory, mood, and cognition as a whole. Through antagonism of these receptors, it induces it's notorious deliriant effects, and causes it's toxicity towards the kidneys, bladder, heart, and brain. It's additionally a blocker of the hERG and sodium channels, the latter of which is the cause of cocaine's cardiotoxicity, and both actions predispose users to arrythmias, physical deteroriation of the heart, and even cardiac arrest. Lastly, it's also an inhibitor of the serotonin, dopamine, and norepinephrine transporters, although this activity is extremely weak, especially it's serotonin transporter inhibition.


Diphenhydramine was discovered in 1943 by George Rieveschl, it was originally used to help with muscle spasms. However, in 1946, it became the first prescription antihistamine approved in the USA, hence known as a "first-generation antihistamine". In the 1980s, diphenhydramine became approved for OTC (over the counter) use as a sleep-aid and allergy medication.


The effects of overdose are similar to the effects of heavy dosages (Look at effects). The threshold for overdose is between 1000-1500mg. Serious side effects of extremely high dosages include arrhythmia (irregular heartbeat), and increased risk of seizures. Physical activity should be avoided due to increased strain in the heart and to avoid Rhabdomyolysis (the breakdown of kidneys). In case of an overdose, it's imperative to call 911 and seek medical help.


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Diphenhydramine (Abbreviated as DPH, most common brand name is Benadryl, though other brands of allergy medication also contain this drug) is an antihistamine medication frequently found over the counter to treat allergies and motion sickness. In addition to its use as a medicine, diphenhydramine has found a niche use as a recreational drug due to its powerful hallucinogenic and deliriant effects at high dosages. Before using diphenhydramine, one should know all of the potential negative effects of use, as it is known for causing negative experiences.



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