Trihexyphenidyl
Trihexyphenidyl is an anticholinergic medicine used alongside other treatment for parkinsonism and to control movement side effects caused by certain psychiatric and other brain-acting medicines.
🧬 Where this information comes from Click to expand
The clinical label records used on this page are FDA-filed Structured Product Labeling (SPL) retrieved through openFDA. We identified 13 clinical label sets within the page’s selected clinical scope after exact ingredient or ingredient-combination matching and applicable route/form matching. Forms, routes, brands, labelers, strengths, and NDC product-record counts are built separately from matching FDA National Drug Code Directory records. The linked DailyMed document is a representative official source for verification, not the page’s only clinical source. View the linked label on DailyMed →
Trihexyphenidyl (Artane) is an older anticholinergic, meaning it blocks acetylcholine, a nerve messenger, used as an add-on for parkinsonism and to ease the stiffness and tremor some antipsychotic medicines cause; it has been on the market since at least the 1980s and is available as a generic. Dry mouth, blurred vision and constipation are what most people notice, and older adults are more prone to confusion and memory slips, so it starts low after 60. Get prompt help for eye pain or vision changes, overheating with little sweating, or new confusion or hallucinations. Never stop it abruptly, which can bring rebound parkinsonism or neuroleptic malignant syndrome, a dangerous reaction.
Clinical pearls
- Taking it before meals helps if dry mouth is the problem, while after meals suits people who drool or get stomach upset.
- Go easy in hot weather, saunas and hard physical work, since it cuts sweating and can let your body overheat.
- Ask for an eye exam that checks your eye's drainage angle (gonioscopy) before starting, plus eye pressure checks over time.
- If you also take levodopa, new writhing or jerky movements may mean one dose needs lowering, so report them.
Patient information guide A plain-language walkthrough of Trihexyphenidyl, written from its FDA label.
What Trihexyphenidyl is used for
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Trihexyphenidyl is used for these conditions:
- Add-on treatment for all forms of parkinsonism (postencephalitic, arteriosclerotic, and idiopathic).
- Add-on to levodopa in these forms of parkinsonism.
- Control of extrapyramidal disorders (movement problems) caused by drugs such as dibenzoxazepines, phenothiazines, thioxanthenes, and butyrophenones.
These uses are listed for Trihexyphenidyl Hydrochloride tablets, oral solution, and syrup.
How Trihexyphenidyl works
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Trihexyphenidyl directly blocks activity of the parasympathetic nervous system. It also relaxes smooth muscle, both directly and indirectly through that nerve effect.
Its effects are similar to atropine, but side effects are usually less frequent and less severe.
Trihexyphenidyl dosage
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Trihexyphenidyl is taken by mouth. Your dose is individualized, starts low, and is increased gradually, especially if you are over 60.
- It may be taken before or after meals, depending on how you react.
- If your mouth gets very dry, before meals may be better unless it upsets your stomach.
- If taken after meals and you get thirsty, mint candies, gum, or water can help.
- With levodopa, the dose of each may need to be lowered.
- Do not stop suddenly.
Follow your prescriber and the label.
Dosing details from the FDA-approved label
From the Trihexyphenidyl prescribing information (“Dosage and Administration”). Doses are set by your prescriber for your product, condition, kidney function and age — never change a dose on your own.
- Idiopathic Parkinsonism
- 1 mg of trihexyphenidyl HCl may be administered the first day
- The dose may then be increased by 2 mg increments at intervals of three to five days, until a total of 6 to 10 mg is given daily
- Some patients, chiefly those in the postencephalitic group, may require a total daily dose of 12 to 15 mg
- Initial dose should be low and increased gradually, especially in patients over 60 years of age; total daily intake is tolerated best divided into 3 doses taken at mealtimes; high doses (>10 mg daily) may be divided into 4 parts, with the fourth at bedtime
- Drug-Induced Parkinsonism
- Total daily dosage usually ranges between 5 and 15 mg, although in some cases as little as 1 mg daily has controlled reactions
- It may be advisable to commence therapy with a single 1 mg dose
- If extrapyramidal manifestations are not controlled in a few hours, subsequent doses may be progressively increased until satisfactory control is achieved
- Size and frequency of dose must be determined empirically; the tranquilizer dose may be temporarily reduced when starting trihexyphenidyl
- Concomitant use with levodopa
- 3 to 6 mg daily, in divided doses, is usually adequate
- The usual dose of each may need to be reduced; careful adjustment depending on side effects and degree of symptom control
- Concomitant use with other parasympathetic inhibitors
- May be substituted, in whole or in part, for other parasympathetic inhibitors
- Usual technique is partial substitution initially, with progressive reduction in the other medication as the trihexyphenidyl dose is increased
Read the label’s full dosing text
DOSAGE AND ADMINISTRATION Dosage should be individualized. The initial dose should be low and then increased gradually, especially in patients over 60 years of age. Whether trihexyphenidyl HCl may best be given before or after meals should be determined by the way the patient reacts. Postencephalitic patients, who are usually more prone to excessive salivation, may prefer to take it after meals and may, in addition, require small amounts of atropine which, under such circumstances, is sometimes an effective adjuvant. If trihexyphenidyl HCl tends to dry the mouth excessively, it may be .better to take it before meals, unless it causes nausea. If taken after meals, the thirst sometimes induced can be allayed by mint candies, chewing gum or water. Abrupt withdrawal of treatment for parkinsonism may result in acute exacerbation of parkinsonism symptoms; therefore, abrupt withdrawal should be avoided. Abrupt withdrawal of treatment may result in neuroleptic malignant syndrome (NMS) ( see WARNINGS ). Idiopathic Parkinsonism As initial therapy for parkinsonism, 1 mg of trihexyphenidyl HCl in tablet form may be administered the first day. The dose may then be increased by 2 mg increments at intervals of three to five days, until a total of 6 to 10 mg is given daily. The total daily dose will depend upon what is found to be the optimal level. Many patients derive maximum benefit from this daily total of 6 to 10 mg, but some patients, chiefly those in the postencephalitic group, may require a total daily dose of 12 to 15 mg. Drug-Induced Parkinsonism The size and frequency of the trihexyphenidyl HCl dose needed to control extrapyramidal reactions to commonly employed tranquilizers, notably the phenothiazines, thioxanthenes, and butyrophenones, must be determined empirically. The total daily dosage usually ranges between 5 and 15 mg although, in some cases, these reactions have been satisfactorily controlled with as little as 1 mg daily. It may be advisable to commence therapy with a single 1 mg dose. If the extrapyramidal manifestations are not controlled in a few hours, the subsequent doses may be progressively increased until satisfactory control is achieved.
Excerpted — the section continues on the label. Read the full Dosage and Administration section on DailyMed →
Trihexyphenidyl side effects
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Minor side effects are common, affecting 30 to 50 percent of patients. They often lessen as treatment continues.
Common side effects
- Dry mouth
- Blurred vision
- Dizziness
- Mild nausea
- Nervousness
- Constipation
- Drowsiness
- Urinary hesitancy or trouble urinating
- Trouble starting urination or emptying the bladder
When to get medical help
- Blurred vision or eye problems: narrow angle glaucoma can worsen, and blindness has been reported. Contact your doctor promptly.
- Fever, muscle stiffness, confusion, or irregular pulse or blood pressure, especially after reducing or stopping the medicine. These can be signs of neuroleptic malignant syndrome, which can be fatal.
- Little or no sweating, or overheating, especially in hot weather. Severe lack of sweating and fatal overheating have occurred with anticholinergics.
- New confusion, memory problems, hallucinations, delusions, or paranoia.
- Severe constipation or belly swelling, or being unable to pass urine.
- Worsening parkinsonism symptoms after missing doses or stopping.
Contact your doctor about eye problems, confusion, hallucinations, overheating, or severe constipation or urinary retention.
Trihexyphenidyl warnings and precautions
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- Glaucoma: it can precipitate angle closure and raise eye pressure. Blindness has been reported.
- Overheating: reduced sweating can lead to hyperthermia (dangerously high body temperature), especially in hot weather.
- Neuroleptic malignant syndrome: a potentially fatal reaction reported with dose reduction or stopping. Signs include very high fever, muscle rigidity, altered mental status, and an unstable pulse or blood pressure.
- Stopping suddenly can also worsen parkinsonism.
Trihexyphenidyl interactions
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Trihexyphenidyl can clash with several types of medicines and substances.
- Alcohol and CNS depressants: more sedation.
- Cannabinoids, barbiturates, opiates: additive effects and abuse potential.
- MAO inhibitors and some tricyclic antidepressants: stronger anticholinergic effects.
- Levodopa: may increase involuntary movements, so doses may need lowering.
- Neuroleptics: possible increased risk of tardive dyskinesia (uncontrolled movements).
Interactions listed in the FDA-approved label
From the Trihexyphenidyl prescribing information (“Drug Interactions”): what the manufacturer studied or reported to the FDA.
- Cannabinoids, barbiturates, opiates, and alcohol: May have additive effects with trihexyphenidyl HCl, and thus an abuse potential exists.
- Alcohol or other CNS depressants: Concurrent use with trihexyphenidyl HCl may cause increased sedative effects.
- Monoamine oxidase inhibitors and tricyclic antidepressants with significant anticholinergic activity: May intensify the anticholinergic effects of antidyskinetic agents because of their secondary anticholinergic activities.
- Neuroleptics: There may be an increased risk for the development of tardive dyskinesia during concomitant administration of anticholinergics and neuroleptics. Prophylactic administration of anticholinergic agents such as trihexyphenidyl to prevent drug-induced parkinsonism during neuroleptic therapy is not recommended.
- Levodopa: Concomitant administration may increase drug-induced involuntary movements. The usual dose of either trihexyphenidyl or levodopa may need to be reduced during concomitant therapy.
Read the label’s full interactions text
Drug Interactions Cannabinoids, barbiturates, opiates, and alcohol may have additive effects with trihexyphenidyl HCl, and thus, an abuse potential exists. Concurrent use of alcohol or other CNS depressants with trihexyphenidyl HCl may cause increased sedative effects. Monoamine oxidase inhibitors and tricyclic antidepressants possessing significant anticholinergic activity may intensify the anticholinergic effects of antidyskinetic agents because of the secondary anticholinergic activities of these medications. Prophylactic administration of anticholinergic agents, such as trihexyphenidyl, as a prevention of drug-induced parkinsonism during neuroleptic therapy is not recommended. There may be an increased risk for the development of tardive dyskinesia during concomitant administration of anticholinergics and neuroleptics ( see PRECAUTIONS , General ) . The usual dose of either trihexyphenidyl or levodopa may need to be reduced during concomitant therapy, since concomitant administration may increase drug-induced involuntary movements ( see DOSAGE AND ADMINISTRATION ).
Not a complete list. The label covers the interactions the manufacturer studied or reported, and our own interaction database does not cover every medicine either. Bring your full medication list, including vitamins and herbal products, to your pharmacist.
Before taking Trihexyphenidyl
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- Do not use if allergic to trihexyphenidyl or any ingredient.
- Do not use with narrow angle glaucoma.
- An eye exam and eye pressure monitoring are advised before and during treatment.
- Use caution in hot weather or hot work environments.
- Use extra caution if chronically ill, an alcoholic, or if you have central nervous system disease.
- Over age 60: a low start and slow increases are advised.
Trihexyphenidyl overdose
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Too much can cause central anticholinergic syndrome: dilated pupils, warm dry flushed skin, fast heartbeat, fever, urinary retention, confusion, agitation, hallucinations, and seizures. It can progress to coma, breathing and heart stopping, and death. Treatment is supportive and symptom-based, and limiting absorption of the drug should be started. Get emergency help right away.
What Trihexyphenidyl does in the body
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Trihexyphenidyl inhibits the parasympathetic nervous system and relaxes smooth muscle. Its effects resemble atropine, but with side effects that are ordinarily less frequent and severe.
How to store Trihexyphenidyl
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Store at 20° to 25°C (68° to 77°F) .
Written from the FDA-approved label with AI and reviewed by our pharmacy team. How we use AI →
Supplements & herbs that interact with Trihexyphenidyl
46 supplements and herbal products have documented interactions with Trihexyphenidyl in the licensed clinical database we use. Most are manageable — but your pharmacist should know about everything you take, including vitamins and herbals.
- Major · 3
- Moderate · 32
- Minor · 11
Educational information from a licensed clinical database (Natural Medicines) — see our data sources & update cadence. Not medical advice: an interaction being documented does not mean it will happen to you; do not start or stop medications or supplements without professional guidance.
Trihexyphenidyl: pharmacist answers to common questions
Quick, plain-English answers to the questions patients ask most about Trihexyphenidyl — the kind of thing our pharmacy team would talk through with you at the counter.
What am I taking this for?
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Should I take it with food?
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What side effects should I expect?
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Can I stop it if I feel better?
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When should I call my doctor?
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Is it okay to drink alcohol?
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Is Trihexyphenidyl available over the counter?
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When was Trihexyphenidyl first available?
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Who makes Trihexyphenidyl?
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Answers drafted from the FDA-approved label with AI and reviewed by our pharmacy team. How we use AI →
More about Trihexyphenidyl on HelloPharmacist
Trihexyphenidyl forms and strengths (how it comes)
Trihexyphenidyl is available in 2 forms. Different forms and brands can have different approved uses, doses, schedules, and directions. Follow the instructions for your exact product, and do not switch forms without guidance from your prescriber or pharmacist.
Need a version that does not list lactose, a gluten source, a dye or gelatin? Inactive ingredients differ by manufacturer: see Trihexyphenidyl inactive ingredients by manufacturer.
Tablet
How this form is used
- Trihexyphenidyl Hydrochloride tablets are used as an add-on treatment for parkinsonism.
- Trihexyphenidyl Hydrochloride tablets are used to control movement side effects caused by certain central nervous system drugs.
- Trihexyphenidyl Hydrochloride tablets are taken by mouth, with dosing individualized and raised gradually.
- Trihexyphenidyl Hydrochloride tablets should not be stopped abruptly.
Oral solution
How this form is used
- Trihexyphenidyl Hydrochloride oral solution is used as an add-on treatment for parkinsonism.
- Trihexyphenidyl Hydrochloride oral solution is used to control movement side effects caused by certain central nervous system drugs.
- Trihexyphenidyl Hydrochloride oral solution is taken by mouth, with dosing individualized and raised gradually.
- Trihexyphenidyl Hydrochloride oral solution should not be stopped abruptly.
Trihexyphenidyl on the U.S. market: products, makers and brands
How Trihexyphenidyl appears in the FDA’s National Drug Code Directory — including its dosage forms, strengths, brand names, manufacturers, and FDA-listed product records. These are directory records, not sales or prescription volume.
9 companies list 17 Trihexyphenidyl product records with the FDA, mostly as tablet, oral solution; the earliest marketing or approval year on record is 1949. Brand names on the directory include Artane, Tremin; the rest are generics.
FDA-listed product records by dose form (tablet variants merged) — FDA National Drug Code Directory. Record counts are not sales or prescription volume.
Also listed with the FDA, not a patient dose form: Powder (4) — bulk drug substance sold to compounders/manufacturers and multi-item kits. These aren’t counted in the dose-form total above.
Share of FDA-listed product records by manufacturer — FDA National Drug Code Directory. Record counts are not sales or prescription volume.
How widely Trihexyphenidyl is used (Medicaid data)
A general measure of how commonly Trihexyphenidyl is prescribed, based on Medicaid — one of the largest public drug programs. The figure below is prescriptions filled in Q1–Q4 2025, summed across every form and brand of the drug.
Think of this as a proxy for how widely Trihexyphenidyl is used, drawn from freely available public data. Medicaid is just one program — these numbers don’t include Medicare, other government coverage, or commercial and cash-pay prescriptions, so real-world use is higher than what’s shown here.
How commonly is Trihexyphenidyl prescribed? Of the 1,601 medications we measure, Trihexyphenidyl ranks #508 by Medicaid prescriptions — more than 68% of them.
Utilization by Trihexyphenidyl product
Pick a product to see its own Medicaid numbers. Each chip is one clinical product — a specific strength & dosage form as defined by RxNorm — with brand-name and generic versions combined.
trihexyphenidyl hydrochloride 2 MG Oral Tablet Most dispensed
Summed across the 5 of 29 listed NDC products with Medicaid activity — every brand and generic of this exact strength & form. RxNorm 905269
trihexyphenidyl hydrochloride 5 MG Oral Tablet
Summed across the 4 of 31 listed NDC products with Medicaid activity — every brand and generic of this exact strength & form. RxNorm 905283
trihexyphenidyl hydrochloride 0.4 MG/ML Oral Solution
Summed across the 1 of 2 listed NDC products with Medicaid activity — every brand and generic of this exact strength & form. RxNorm 905273
Shares are of the Medicaid prescriptions shown here. Product grouping follows RxNorm (the National Library of Medicine’s drug terminology), so “one product” means one strength & dosage form regardless of manufacturer. Dollar figures are gross Medicaid reimbursement before mandatory rebates — rebates (often large, especially for brand-name drugs) are confidential, so actual net cost to Medicaid is lower than shown.
Source: Medicaid State Drug Utilization Data (CMS), aggregated by generic ingredient — summed across every NDC (all brands, strengths, salt forms and dosage forms) of Trihexyphenidyl, and across all states and both fee-for-service and managed-care claims. A general popularity signal; it excludes Medicare, commercial insurance and cash prescriptions, so it is not total U.S. use. Based on the 10 of 62 listed Trihexyphenidyl NDCs with Medicaid activity.
Compare Trihexyphenidyl products
A representative set of FDA-listed product records for Trihexyphenidyl — across manufacturers, strengths, and dosage forms, grouped by form with each product’s manufacturer and how the FDA approved it. The same medicine may be made and packaged by different companies, so a single drug can have many directory entries. (It’s also why a refill can look different — a new shape, color, or box — even though it contains the same medication.)
| Strength | Route | Manufacturer / Labeler | Category ⓘ | Details |
|---|---|---|---|---|
| 💊Oral solution | ||||
| 2 mg/5 mL | Oral | Akorn | ANDA | View NDC → |
| 2 mg/5 mL | Oral | Chartwell RX, LLC | ANDA | View NDC → |
| 2 mg/5 mL | Oral | PAI Holdings, LLC dba PAI Pharma | ANDA | View NDC → |
| 💊Tablet | ||||
| 2 mg | Oral | Actavis Pharma, Inc. | ANDA | View NDC → |
| 5 mg | Oral | Actavis Pharma, Inc. | ANDA | View NDC → |
| 2 mg | Oral | Bionpharma Inc. | ANDA | View NDC → |
| 2 mg | Oral | Golden State Medical Supply Inc. | ANDA | View NDC → |
| 5 mg | Oral | Golden State Medical Supply Inc. | ANDA | View NDC → |
| 2 mg | Oral | Natco Pharma Limited | ANDA | View NDC → |
| 5 mg | Oral | Natco Pharma Limited | ANDA | View NDC → |
| 2 mg | Oral | Novitium Pharma LLC | ANDA | View NDC → |
| 5 mg | Oral | Novitium Pharma LLC | ANDA | View NDC → |
| 2 mg | Oral | Remedyrepack Inc. × 2 listings | ANDA | View NDC → |
| 5 mg | Oral | Remedyrepack Inc. × 3 listings | ANDA | View NDC → |
Showing 17 of 17 products — FDA National Drug Code Directory. See every product, package size and price: browse all 17 Trihexyphenidyl NDCs →
Trihexyphenidyl side effects reported to the FDA (FAERS)
After a medicine reaches the market, patients, doctors and drugmakers can send the FDA reports of problems they think may be linked to it. Here’s what’s been reported for Trihexyphenidyl — a signal of what to watch for, not proof the drug caused it.
Source: openFDA, from the FDA Adverse Event Reporting System (FAERS). These are voluntary reports — they don’t prove the drug caused the effect, and counts reflect how often something was reported, not how often it actually happens. Reports also often name the very problem the medicine is taken for — a common reason to file one is that the drug didn’t help — so for a pain reliever you may see “pain” high on the list; that points to why the report was filed, not to the drug causing the symptom. This counts every report that lists Trihexyphenidyl in any role, so the total runs higher than the FDA’s official dashboard, which counts only cases where the drug is the suspect. For the authoritative figures, see the FDA FAERS Public Dashboard. Always talk to your pharmacist or doctor.
Trihexyphenidyl FDA approval history
How Trihexyphenidyl went from FDA review to the pharmacy shelf — the key milestones in its regulatory journey.
Source: Drugs@FDA.
Trihexyphenidyl recall history
A recall is when a specific batch of a medicine is pulled from the market — usually a manufacturing issue, not a problem with the drug itself. Class I is most serious, Class III least.
The FDA’s enforcement reports list no Trihexyphenidyl recalls since July 2021.
✅No Trihexyphenidyl recalls on record since July 2021Source: FDA enforcement (recall) reports, via openFDA; our copy was last updated Sep 24, 2026.
RxNorm Concept Web — From Ingredient to Every Form and Strength
This page starts with one ingredient concept (IN). The branches below show its dose-form concepts (SCDF), then the available clinical drug and strength concepts (SCD). Combination products remain separate concepts with their own pages.
RxCUI 10811 2 dose forms · 4 strengths
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Dose form (SCDF) Oral Solution RxCUI 374213In current FDA listingsClinical drug / strength (SCD) hydrochloride 0.4 MG/MLRxCUI 905273hydrochloride 1 MG/MLRxCUI 905292 -
Dose form (SCDF) Oral Tablet RxCUI 374214In current FDA listings
Look up RxCUI 10811 in the RxCUI Atlas →
RxNorm is the U.S. National Library of Medicine’s normalized drug vocabulary. Its concept hierarchy can include forms that are not currently marketed; the status on each branch compares that concept with current FDA listings. RxCUIs identify vocabulary concepts, not individual packages or manufacturers.
Trihexyphenidyl supply and shortage status
Whether Trihexyphenidyl is in short supply in the U.S. right now, plus any shortage history the FDA has on record. A shortage usually reflects a manufacturing or demand issue — not a safety problem with the drug.
Source: openFDA, from the FDA Drug Shortages database.
💵 What Trihexyphenidyl costs pharmacies (NADAC benchmark)
The national average invoice price pharmacies pay for the drug itself, from CMS's NADAC survey (data as of Sep 30, 2026). This is a supply-cost benchmark — not a retail price and not what you'd pay at the counter.
| Form | Strength | Pharmacy acquisition benchmark | |
|---|---|---|---|
| Tablet · Oral | 5 mg | $0.119 per tablet | NDC details & price history |
| Tablet · Oral | 2 mg | $0.088 per tablet | NDC details & price history |
| Solution · Oral | 2 mg/5 mL | $0.159 per mL | NDC details & price history |
| Tablet | 2 mg | $0.088 per tablet | NDC details & price history |
| Tablet | 5 mg | $0.119 per tablet | NDC details & price history |
Source: CMS National Average Drug Acquisition Cost (NADAC), a survey of retail pharmacy invoice prices. Benchmarks shown are the range across package sizes of a representative product for each form and strength — other manufacturers' products may differ.
Trihexyphenidyl brand names
Trihexyphenidyl is sold under 2 brand names in the FDA directory — Artane, Tremin. A brand and its generic contain the same active ingredient; the brand name belongs to one company's product.
Who makes Trihexyphenidyl: manufacturers and labelers
9 companies list Trihexyphenidyl products with the FDA. By number of product records, the largest are Remedyrepack Inc., Actavis Pharma, Inc., Golden State Medical Supply Inc.. Labelers include manufacturers and repackagers; the product in your bottle depends on which one your pharmacy stocks.
Trihexyphenidyl drug class (RxNorm)
Trihexyphenidyl belongs to the Tertiary amines class.
Classified by RxNorm RxClass — the U.S. National Library of Medicine's standardized drug-classification service (Established Pharmacologic Class from the FDA, the ATC drug family from the WHO, and mechanism of action). Reference only, not medical advice.
Sources for this Trihexyphenidyl page
Core label, product, RxNorm, safety, and utilization data on this page come from the sources identified below. AI-written, editorial, and licensed sections are labeled separately.
How this page is built
HelloPharmacist combines public FDA and NLM records and does not author the underlying clinical facts. The plain-language sections are written with AI from the FDA-approved label text and reviewed by our pharmacy team before publication. Bionpharma Inc. is the representative DailyMed label linked for verification and dates. This is general education, not medical advice: always talk to your doctor or pharmacist about your own medicines. How we build and review drug pages →