Dimenhydrinate Stats & Data
NFLLKCVHYJRNRH-UHFFFAOYSA-NPharmacology
DrugBankDescription
Dimehydrinate was first described in the literature in 1949, and patented in 1950. Early research into dimenhydrinate focused on its role as an antihistamine for urticaria; the treatment of motion sickness was an accidental discovery. Dimenhydrinate, also known as B-dimethylaminoethyl benzohydrol ether 8-chlorotheophyllinate, is indicated to prevent nausea, vomiting, and dizziness caused by motion sickness. Dimenhydrinate is a combination of Diphenhydramine and 8-chlorotheophylline in a salt form, with 53%-55.5% dried diphenhydramine, and 44%-47% died 8-chlorotheophylline. The antiemetic properties of dimenhydrinate are primarily thought to be produced by diphenhydramine's antagonism of H1 histamine receptors in the vestibular system while the excitatory effects are thought to be produced by 8-chlorotheophylline's adenosine receptor blockade. When used in large doses, dimenhydrinate has been shown to cause a "high" characterized by hallucinations, excitement, incoordination, and disorientation. Dimenhydrinate was granted FDA approval on 31 May 1972.
Mechanism of Action
Dimenhydrinate is a theoclate salt that separates into diphenhydramine and 8-chlorotheophylline. While the exact mechanism of action is unknown, diphenhydramine is theorized to reduce disturbances to equilibrium through antimuscarinic effects or histamine H1 antagonism. 8-chlorotheophylline may produce excitation through blocking adenosine receptors, reducing the drowsiness produced by diphenhydramine.
Pharmacodynamics
Dimenhydrinate is indicated for the prevention and treatment of nausea, vomiting, or vertigo of motion sickness. It has a short duration of action of 4-8 hours. Patients should be counselled regarding pronounced drowsiness, avoiding alcohol and other sedatives, and exercising caution when operating a motor vehicle or heavy machinery.
Metabolism
Dimenhydrinate is a theoclate salt that separates into diphenhydramine and 8-chlorotheophylline. diphenhydramine can either be N-glucuronidated by UGTs to diphenhydramine N-glucuronide or N-demethylated by CYP2D6, CYP1A2, CYP2C9, and CYP2C19 to N-desmethyldiphenhydramine. N-desmethyldiphenhydramine can be N-demethylated again by the same enzymes to N,N-didesmethyldiphenhydramine, which undergoes oxidative deamination to form diphenylmethoxyacetic acid.
Absorption
A 50 mg oral film coated tablet reaches a Cmax of 72.6 ng/mL with a Tmax of 2.7 hours. A 100 mg suppository reaches a Cmax of 112.2 ng/mL with a Tmax of 5.3 hours.
Indication
Dimenhydrinate is indicated for the prevention and treatment of nausea, vomiting, or vertigo of motion sickness.
Half-life
The plasma elimination half life of dimenhydrinate is 5-8 hours.
Protein Binding
Dimenhydrinate is 70-85% protein bound in plasma.
Elimination
Dimenhydrinate is predominantly eliminated in the urine. 1-3% of the dissociated diphenhydramine is eliminated in the urine unchanged, while 64% of diphenhydramine is eliminated in the urine as metabolites. The elimination of dimenhydrinate has not been fully studied.
Volume of Distribution
The volume of distribution of dimenhydrinate is 3-4 L/kg.
Receptor Profile
Receptor Actions
Receptor Binding
History & Culture
1947–1950
Dimenhydrinate, originally designated Compound 1694, was developed through serendipitous observation rather than targeted research. In 1947, allergists Dr. Leslie Gay and Dr. Paul Carliner at Johns Hopkins Hospital were testing the compound as a potential treatment for hay fever and hives. Among their test subjects was a pregnant woman who had experienced motion sickness throughout her entire life. She discovered that taking dimenhydrinate shortly before boarding a trolley completely prevented her symptoms, while a placebo proved ineffective. These unexpected findings prompted pharmaceutical company G.D. Searle & Co. to conduct formal clinical trials the following year. The company administered dimenhydrinate or placebo to American troops during a ten-day transatlantic voyage aboard the General Ballou, a converted freight ship navigating rough seas. The results were positive, as was a subsequent trial conducted predominantly with women on the ship's return voyage. Gay and Carliner formally announced their discovery at a meeting of the Johns Hopkins Medical Society on February 14, 1949. G.D. Searle introduced the drug to the market under the brand name Dramamine later that year. The compound was first described in scientific literature in 1949 and received patent protection in 1950.
Beyond its medical applications, dimenhydrinate has gained recognition for its recreational use as a deliriant substance. Users have developed various slang terms for this practice, including "drama," "dime," "dime tabs," "D-Q," "substance D," "d-house," and "drams." The act of using the drug recreationally is sometimes called "dramatizing" or "going a dime a dozen," the latter being a reference to the number of tablets typically required to achieve deliriant effects. The substance has also appeared in popular music. Modest Mouse released a song titled "Dramamine" on their 1996 debut album "This Is a Long Drive for Someone with Nothing to Think About," employing the drug's side effects as a metaphor for a deteriorating personal relationship. Car Seat Headrest later featured "The Ending of Dramamine" as the opening track on their album "How to Leave Town."
The toxicity and long-term health effects of recreational diphenhydramine use have not been studied extensively. Diphenhydramine can be highly unpredictable, and the mechanism by which it produces hallucinations has the potential to result in serious injury, hospitalization, or death. Additionally, diphenhydramine puts users in a state where they have little control over their actions. Diphenhydramine can provoke bizarre and nonsensical behavior, which may put the user at risk. Anecdotal reports suggest that regular use of diphenhydramine can have profound effects on one's kidneys and bladder, with the potential to result in issues similar to that of ketamine cystitis.
Liver injury risk
No documented concern
Overdose
The overdose threshold for diphenhydramine is commonly held to be around 1000 milligrams; however, sensitive individuals or individuals taking other drugs alongside it can overdose with less. The main effects of an overdose are similar to those of heavy doses. Effects include delirium, psychosis, anxiety, confusion, hypotension, dryness, urinary retention, dizziness, dilated pupils and increased heart rate.
Addiction & dependence
Diphenhydramine produces dependence with chronic use. In comparison to other hallucinogens, DPH has been reported to have significantly less abuse potential than other hallucinogens. Most people who try it do not wish to repeat the experience.
Toxicity (DrugBank)
Infants and children experiencing an overdose may lead to hallucinations, convulsions, or death. Adults experiencing an overdose may present with drowsiness, convulsions, coma, or respiratory depression. Treat overdoses with symptomatic and supportive measures including mechanically assisted ventilation. In mice the oral LD50 is 203 mg/kg, while in rats it is 1320 mg/kg. The intraperitoneal LD50 in mice is 149 mg/kg.
Tolerance & Pharmacokinetics
drugs.wikiTolerance Decay
Anecdotal reports suggest rapid tolerance to deliriant/anticholinergic cognitive and hallucinatory effects with repeated dosing over days, with partial reversal over 1–2 weeks. Data quality low; avoid frequent use to reduce cumulative anticholinergic burden.
Cross-Tolerances
Experience Report Analysis
ErowidDemographics
Gender Distribution
Age Distribution
Reports Over Time
Effect Analysis
ErowidEffects aggregated from 154 experience reports (154 single-substance Erowid)
Effect Sentiment Distribution
Confidence Distribution
Each bar is the share of reports mentioning the effect; its whisker, and the band on the rows below, is the 95% interval: where the share could plausibly be with other reports of the same kind.
Positive Effects 10
Adverse Effects 12
Show 7 neutral or unclassified mentions
Also reported in combinations. In the 67 Dimenhydrinate reports where another drug was taken too, 12 (17.9%) mention hospital, emergency services or an overdose, 3 (4.5%) a seizure and 3 (4.5%) psychosis. In the 154 single-substance reports: 17.5%, 3.9% and 4.5%. These are not in the figures above: they cannot be put down to Dimenhydrinate alone, and a mention is not always something that happened to the writer.
Dose-Response Correlation
How effect frequency changes across dose levels. Whiskers, and the numbers' hover text, give each figure's 95% interval.
View data table
| Effect | Strong (n=21) | Heavy (n=71) |
|---|---|---|
| Visual Distortions | 71.4% (95% interval 50 to 86 percent) | 46.5% (95% interval 35 to 58 percent) |
| Anxiety | 61.9% (95% interval 41 to 79 percent) | 67.6% (95% interval 56 to 77 percent) |
| Sedation | 57.1% (95% interval 36 to 76 percent) | 39.4% (95% interval 29 to 51 percent) |
| Auditory Effects | 38.1% (95% interval 21 to 59 percent) | 46.5% (95% interval 35 to 58 percent) |
| Open-Eye Visuals | 33.3% (95% interval 17 to 55 percent) | 39.4% (95% interval 29 to 51 percent) |
| Memory Suppression | 38.1% (95% interval 21 to 59 percent) | 29.6% (95% interval 20 to 41 percent) |
| Confusion | 33.3% (95% interval 17 to 55 percent) | 33.8% (95% interval 24 to 45 percent) |
| Stimulation | 33.3% (95% interval 17 to 55 percent) | 19.7% (95% interval 12 to 30 percent) |
| Focus Enhancement | 28.6% (95% interval 14 to 50 percent) | 4.2% (95% interval 1 to 12 percent) |
| Color Enhancement | 23.8% (95% interval 11 to 45 percent) | 28.2% (95% interval 19 to 40 percent) |
| Music Enhancement | 23.8% (95% interval 11 to 45 percent) | 23.9% (95% interval 16 to 35 percent) |
| Nausea | 23.8% (95% interval 11 to 45 percent) | 16.9% (95% interval 10 to 27 percent) |
| Closed-Eye Visuals | 19.0% (95% interval 8 to 40 percent) | 19.7% (95% interval 12 to 30 percent) |
| Euphoria | 19.0% (95% interval 8 to 40 percent) | 16.9% (95% interval 10 to 27 percent) |
| Motor Impairment | 19.0% (95% interval 8 to 40 percent) | 16.9% (95% interval 10 to 27 percent) |
Subjective Effect Ontology
Experience ReportsStructured effect tags extracted from 221 experience reports using a controlled vocabulary of 220+ canonical effects across 15 domains.
Emotional
Visual
Dose–Effect Mapping
Experience ReportsHow reported effects shift across dose tiers, based on 154 single-substance experience reports. The shaded band on each bar is its 95% interval. An arrow (↑ ↓) marks a change between the lowest and highest tier that count an effect only when the gap is bigger than chance would explain; ~ means no clear change. How changes are called
Limited tier coverage — most reports fall within the Strong / Heavy range. Effects at other dose levels may not be represented.
| Effect | Strong (n=21) | Heavy (n=71) | Change with dose |
|---|---|---|---|
| visual distortions | (−25 points from Strong to Heavy, 95% interval −43 to −1) | ||
| anxiety | (no clear change: +6 points from Strong to Heavy, 95% interval −15 to +29) | ||
| sedation | (no clear change: −18 points from Strong to Heavy, 95% interval −39 to +6) | ||
| auditory effects | (no clear change: +8 points from Strong to Heavy, 95% interval −15 to +29) | ||
| open-eye visuals | (no clear change: +6 points from Strong to Heavy, 95% interval −18 to +26) | ||
| memory suppression | (no clear change: −8 points from Strong to Heavy, 95% interval −32 to +12) | ||
| confusion | (no clear change: +0.5 points from Strong to Heavy, 95% interval −23 to +20) | ||
| stimulation | (no clear change: −14 points from Strong to Heavy, 95% interval −36 to +6) | ||
| focus enhancement | (−24 points from Strong to Heavy, 95% interval −46 to −8) | ||
| color enhancement | (no clear change: +4 points from Strong to Heavy, 95% interval −19 to +22) | ||
| music enhancement | (no clear change: +0.1 points from Strong to Heavy, 95% interval −23 to +17) | ||
| nausea | (no clear change: −7 points from Strong to Heavy, 95% interval −29 to +10) | ||
| closed-eye visuals | (no clear change: +1 points from Strong to Heavy, 95% interval −22 to +16) | ||
| euphoria | (no clear change: −2 points from Strong to Heavy, 95% interval −24 to +13) | ||
| motor impairment | (no clear change: −2 points from Strong to Heavy, 95% interval −24 to +13) | ||
| body high | (no clear change: −10 points from Strong to Heavy, 95% interval −32 to +4) | ||
| hospital | (no clear change: +9 points from Strong to Heavy, 95% interval −12 to +21) | ||
| jaw clenching | — | counted in the Strong tier only | |
| dissociation | (no clear change: −2 points from Strong to Heavy, 95% interval −23 to +12) | ||
| pupil dilation | (no clear change: +2 points from Strong to Heavy, 95% interval −18 to +13) |
Showing top 20 of 30 effects
Risk Escalation
Sentiment AnalysisAverage frequency of positive vs adverse effects across dose tiers. A tier's average is the mean share of the effects counted in that tier, not a share of reports, and its range is a deliberately wide 95% interval. A tier with more reports also counts rarer effects, which pulls its average down, so compare single effects in the breakdown rather than these averages. There, the shaded band on each bar is its 95% interval, and Change is marked up or down only when the gap between two tiers is bigger than chance would explain. How changes are called
View effect breakdown
Adverse Effects
| Effect | Strong (n=21) | Heavy (n=71) | Change |
|---|---|---|---|
| Anxiety | no clear change (no clear change: +6 points from Strong to Heavy, 95% interval −15 to +29) | ||
| Memory Suppression | no clear change (no clear change: −8 points from Strong to Heavy, 95% interval −32 to +12) | ||
| Confusion | no clear change (no clear change: +0.5 points from Strong to Heavy, 95% interval −23 to +20) | ||
| Nausea | no clear change (no clear change: −7 points from Strong to Heavy, 95% interval −29 to +10) | ||
| Motor Impairment | no clear change (no clear change: −2 points from Strong to Heavy, 95% interval −24 to +13) | ||
| Jaw Clenching | — | — | |
| Pupil Dilation | no clear change (no clear change: +2 points from Strong to Heavy, 95% interval −18 to +13) | ||
| Headache | no clear change (no clear change: −4 points from Strong to Heavy, 95% interval −24 to +7) | ||
| Psychosis | — | — | |
| Sweating | — | — | |
| Seizure | — | — | |
| Increased Heart Rate | — | — | |
| Muscle Tension | — | — |
Positive Effects
| Effect | Strong (n=21) | Heavy (n=71) | Change |
|---|---|---|---|
| Stimulation | no clear change (no clear change: −14 points from Strong to Heavy, 95% interval −36 to +6) | ||
| Focus Enhancement | −24 pts (−24 points from Strong to Heavy, 95% interval −46 to −8) | ||
| Color Enhancement | no clear change (no clear change: +4 points from Strong to Heavy, 95% interval −19 to +22) | ||
| Music Enhancement | no clear change (no clear change: +0.1 points from Strong to Heavy, 95% interval −23 to +17) | ||
| Euphoria | no clear change (no clear change: −2 points from Strong to Heavy, 95% interval −24 to +13) | ||
| Body High | no clear change (no clear change: −10 points from Strong to Heavy, 95% interval −32 to +4) | ||
| Empathy | no clear change (no clear change: −5 points from Strong to Heavy, 95% interval −25 to +5) | ||
| Tactile Enhancement | no clear change (no clear change: −1 points from Strong to Heavy, 95% interval −21 to +10) | ||
| Introspection | — | — |
Dosage Distribution
Dose distribution from experience reports, one dose per report (the first listed). Doses above Q3 + 3×IQR, far above what people typically take, are left out of the median and range and listed under each route: most are real heavy doses or overdoses, not mistakes.
2 reports gave a dose above the typical range (3,000–3,600 mg), so they are not in the figures above. 1 of them mentions hospital, emergency services or an overdose. Listing a dose here does not mean it is safe.
Real-World Dose Distribution
ErowidFrom 266 of 350 recorded dose entries: those that state a weight (mg, g or µg), in routes with at least five of them. Values above Q3 + 3×IQR, far above what people typically take, are left out; they can include real heavy doses and overdoses, not only mistakes.
Oral (n=263)
Common Combinations
Most co-occurring substances, as a share of all 221 reports filed under Dimenhydrinate; whiskers are 95% intervals
Form / Preparation
Most common forms and preparations, as a share of the 185 reports that give one; whiskers are 95% intervals
Body-Weight Dosing
Dose per kg of body weight, one dose per report (the first listed), from reports giving a weight of 30–250 kg. Doses above Q3 + 3×IQR, far above what people typically take, are left out of the median and range and listed under each route.
1 report gave a dose above the typical range (50.847 mg/kg), so it is not in the figures above. It mentions hospital, emergency services or an overdose. Listing a dose here does not mean it is safe.
Show the report
- 50.847 mg/kg · mentions hospital, emergency services or an overdose
Redose Patterns
Redosing behavior across 192 reports
Legal Status
| Country | Status | Notes |
|---|---|---|
| Canada | Legal (OTC/Prescription) | Available over-the-counter as oral tablets (commonly sold under brand name Gravol). Injectable formulations require a prescription and have been marketed since 1973. |
| United States | Legal (OTC/Prescription) | FDA approved on May 31, 1972. Oral tablet formulations are available over-the-counter without prescription. Injectable formulations (50 mg/mL intramuscular/intravenous) are available by prescription. |
Harm Reduction
drugs.wikiDimenhydrinate is a salt that dissociates into diphenhydramine (anticholinergic H1 antihistamine) and 8‑chlorotheophylline (a methylxanthine with adenosine receptor blockade), which can both shape effects and side‑effects. At high doses, users can develop a full anticholinergic toxidrome: agitation, confusion, hallucinations, mydriasis, dry skin/mucosa, urinary retention, hyperthermia, tachycardia, decreased bowel sounds. Onset and peak can be slow (up to ~2–3 hours); redosing early risks stacking and unexpectedly severe delirium. Avoid heat, strenuous activity, or hot environments while intoxicated due to impaired sweating and hyperthermia risk. Do not drive or operate machinery for the rest of the day and potentially the next morning because impairing sedation and vestibular effects may persist beyond the perceived ‘trip.’ People with glaucoma, urinary retention/BPH, or significant pulmonary disease should avoid use without medical supervision due to anticholinergic effects exacerbating these conditions. Children and older adults are more susceptible to delirium, paradoxical excitation, seizures, and serious toxicity; keep products locked away and never use recreationally in these groups. Dimenhydrinate has been associated with QTc prolongation and conduction disturbances at high exposure (largely via diphenhydramine), so avoid combining with other QT‑prolonging drugs and seek care if syncope or palpitations occur. Seizures are a recognized complication of antihistamine toxicity; avoid co‑ingesting agents that lower seizure threshold and seek urgent care if tremor, clonus, or seizure activity appears. If signs of anticholinergic toxicity emerge (confusion, inability to sweat, very hot skin, urinary retention, visual disturbances), seek emergency help; in hospital, benzodiazepines and temperature control are first‑line, and physostigmine may be considered by clinicians for severe pure anticholinergic delirium. Verify the active ingredient on any ‘motion‑sickness’ or ‘original/less drowsy’ products; similarly named brand variants in different markets may contain different actives. Because each 100 mg of dimenhydrinate contains only about 53–55.5 mg of diphenhydramine base, very large ‘recreational’ dimenhydrinate doses can covertly correspond to high diphenhydramine exposure and its cardiotoxic/deliriant risks.
References
Cited References
- Erowid: Dimenhydrinate Vault
- Erowid: Dimenhydrinate FAQ
- NIST Chemistry WebBook: Dimenhydrinate
- PubChem: Dimenhydrinate
- PsychonautWiki: Antihistamine
- PsychonautWiki: Deliriant
- PsychonautWiki: Diphenhydramine
- StatPearls: Diphenhydramine
- TripSit Factsheet: Dramamine
- DrugBank: Ethanolamine derivatives
- Substance Search: Dramamine
Additional references
- DrugBank DB00985: Dimenhydrinate monograph (composition, PK, half‑life, Tmax)
- Erowid Dimenhydrinate Vault (general info, brand names, effects)
- Erowid Dimenhydrinate Health page (contraindications, MAOIs, CNS depressants, glaucoma/BPH cautions, seizures)
- Erowid Dimenhydrinate FAQ (ranges and user‑report context)
- StatPearls: Anticholinergic Toxicity (toxidrome mnemonic, management incl. benzodiazepines/physostigmine; QT issues with diphenhydramine)