Primidone 50 mg Tablet, 500-count
Other active recalls for Primidone (different manufacturers) — 6 · tap to view
🆔 Identity & classification
Where does this data come from?
🏷️ RxNorm drug class
This medicine belongs to the Anti-epileptic Agent class.
Where does this data come from?
🏭 Manufacturer & labeler
Where does this data come from?
🩺 Clinical
- Primidone is a seizure medicine — an anticonvulsant. It's used to control several types of epileptic seizures, including grand mal (major convulsions), psychomotor seizures, and fo...
- Starting low and increasing gradually gives your body time to adjust. The most common early side effects — dizziness, unsteadiness, and nausea — tend to be much milder when the dos...
- Why do I have to start at such a low dose and build up slowly?
- Please don't stop suddenly without talking to your doctor first. Stopping an anticonvulsant abruptly can trigger a prolonged, dangerous seizure called status epilepticus — that's a...
Patient education
Supplement & herbal interactions
Some supplements/herbs that may interact with Primidone — tap one for details:
Primidone may be associated with lower levels of 3 nutrients — worth a chat with your pharmacist, not a cause for alarm.
Where does this data come from?
Ask a licensed pharmacist directly — free, answered by our team.
💊 What it looks like
Where does this data come from?
🧪 Inactive Ingredients / Excipients
Inactive ingredients, also called excipients, are components of the drug product other than the active ingredient. They may include fillers, dyes, coatings, preservatives, flavors, or other formulation ingredients.
💡 Tap an ingredient (hover on desktop) to see what it is and why it’s used.
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UNII OP1R32D61U
Microcrystalline cellulose is a purified form of cellulose, a natural fiber from plant sources. It acts as a binder and filler in tablets and capsules, helping hold ingredients together and give the medicine its shape and size.
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UNII EWQ57Q8I5X
Lactose monohydrate is a natural sugar derived from milk. It serves as a filler and binder in tablets and capsules, helping create the proper size, texture, and consistency of the medicine.
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UNII 70097M6I30
Magnesium stearate is a salt made from magnesium and stearic acid, a fatty substance. It's used in tablets and capsules as a lubricant and glidant to help ingredients flow smoothly during manufacturing and prevent sticking.
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UNII 4GFU244C4J
Methylcellulose is a plant-based thickening agent made from cellulose. It acts as a binder to hold pill ingredients together and as a bulking agent to add texture and consistency to liquid or semi-solid medicines.
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UNII 368GB5141J
A detergent and foaming agent derived from coconut or palm oil. In medications, it helps break down and mix oil and water-based ingredients, aids in tablet disintegration, and improves how the drug dissolves and spreads in the mouth or digestive system.
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UNII 5856J3G2A2
A starch-based powder made from potatoes and processed with sodium. It acts as a disintegrant, helping the tablet or capsule break apart quickly in the stomach so the medicine can be absorbed.
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UNII O8232NY3SJ
A plant-based carbohydrate derived from corn kernels. It acts as a filler to add bulk, a binder to hold ingredients together, and a disintegrant to help the tablet break apart in your stomach for absorption.
7 inactive ingredients listed in the exact product block matched to this NDC.
Where does this data come from?
ingredient classCode="IACT" elements from the exact product block matched by this NDC. Label-section narrative from DailyMed / the openFDA label index is shown separately when available.Inactive ingredient FAQ
Are inactive ingredients the same for every manufacturer?
Why might an inactive ingredient be missing?
Can inactive ingredients matter?
💲 Pricing
A drug doesn't have one price. Each row is a different public payment system, and none is what you'd pay at the counter — that depends on your insurance. The ⓘ on each row explains what it measures.
| Price system | Per each | Per package |
|---|---|---|
| Retail pharmacies payNADAC · weekly | Not in the retail survey — common for institutional, discontinued, or low-volume packs. | |
| Medicaid paysCMS SDUD · 12 mo | No recent Medicaid claims on file for this NDC — rare and low-volume NDCs are suppressed in the public data. | |
| Medicare drug plans payPart D · Q2 2026 | $0.1997 | $99.85 / 500 tablets |
Where does this data come from?
🔁 Therapeutic equivalents
| Product | Labeler | Pack | NADAC/unit | TE | Status | Price vs. this |
|---|---|---|---|---|---|---|
| Primidone 50 mg 00527-1301-01 | Lannett | 100 tablets | $0.092 | AB | Availability likely | — |
| Primidone 50 mg 50268-0686-15 | AvPAK | 50 tablets | $0.092 | AB | Availability likely | — |
| Primidone 50 mg 53746-0544-01 | Amneal | 100 tablets | $0.092 | AB | Availability likely | — |
| Primidone 50 mg 62135-0468-90 | Chartwell | 90 tablets | $0.092 | AB | Availability likely | — |
| Primidone 50 mg 68084-0202-01 | American | 100 tablets | $0.092 | AB | Availability likely | — |
| Primidone 50 mg 69584-0684-10 | Oxford | 100 tablets | $0.092 | AB | Availability likely | — |
| Primidone 50 mg 72603-0609-01 | NorthStar | 100 tablets | $0.092 | AB | Availability likely | — |
| Primidone 50 mg 72888-0045-01 | Advagen | 100 tablets | $0.092 | AB | Availability likely | — |
| Primidone 50 mg 80005-0117-11 | Carnegie | 100 tablets | $0.092 | AB | Availability likely | — |
| Primidone 50 mg 65162-0544-10 | Amneal | 100 tablets | $0.134 | AB | FDA listed | — |
| Primidone 50 mg 00615-8206-30 | NCS | 30 tablets | — | AB | Discontinued | — |
| Primidone 50 mgthis 42291-0509-50 | AvKARE | 500 tablets | — | AB | FDA listed | — |
| Primidone 50 mg 51407-0637-01 | Golden | 100 tablets | — | AB | FDA listed | — |
| Primidone 50 mg 55111-0477-01 | Dr. | 100 tablets | — | — | FDA listed | — |
| Primidone 50 mg 63629-7811-01 | Bryant | 30 tablets | — | AB | FDA listed | — |
| Mysoline 50 mg 66490-0690-10 | Bausch | 100 tablets | — | AB | FDA listed | — |
| Primidone 50 mg 71335-1965-01 | Bryant | 30 tablets | — | AB | FDA listed | — |
| Primidone 50 mg 71610-0540-09 | Aphena | 9000 tablets | — | AB | FDA listed | — |
| Primidone 50 mg 71610-0590-60 | Aphena | 90 tablets | — | AB | FDA listed | — |
| Primidone 50 mg 71610-0763-60 | Aphena | 90 tablets | — | AB | FDA listed | — |
| Primidone 50 mg 72189-0216-60 | DIRECT | 60 tablets | — | AB | FDA listed | — |
| Primidone 50 mg 72789-0178-01 | PD-Rx | 100 tablets | — | AB | FDA listed | — |
| Primidone 50 mg 82804-0952-00 | Proficient | 100 tablets | — | AB | FDA listed | — |
| Primidone 50 mg 00615-8664-39 | NCS | 30 tablets | — | AB | FDA listed | — |
Where does this data come from?
⏳ Availability & generic status
This product is an FDA-approved generic. Other versions of the same drug are listed under Therapeutic equivalents, least expensive first.
Where does this data come from?
📊 Medicare Part D spend CMS · PART D · 2026 (Q1)
🔬 Reported adverse events (FAERS)
Top reported reactions
Age at onset
Reporter sex
Serious outcomes
Where does this data come from?
📦 Packaging — all sizes for this product
| Package NDC | Description | Marketing start | Status |
|---|---|---|---|
| 42291-0509-01 | 100 TABLET in 1 BOTTLE (42291-509-01) | 2022-03-22 | Discontinued by firm |
| 42291-0509-50 You're viewing this | 500 TABLET in 1 BOTTLE (42291-509-50) | 2022-03-22 | Active |
You're viewing the largest of 2 pack sizes for this product.
Pack size FAQ
What quantity is in NDC 42291-0509-50?
What is the difference between NDC 42291-0509-50 and NDC 42291-0509-01?
What NDC number is used to bill for this package of Primidone 50 mg Tablet?
🧭 About this NDC listing & data coverage
What data is (and isn’t) available for this NDC — tap to expand
| NDC identity (package / product / labeler codes) | ✓ Available |
| Labeler | ✓ Available |
| Product & package description | ✓ Available |
| Marketing category & status | ✓ Available |
| Active ingredient / dosage form / route | ✓ Available |
| FDA label (SPL via DailyMed) | ✓ Available |
| Package photos | ✓ Available |
| Inactive ingredients (structured) | ✓ Available |
| NADAC pharmacy acquisition price (CMS) | — Not published for this NDC CMS publishes NADAC only for NDCs reported in its retail-pharmacy survey. |
| Orange Book / therapeutic-equivalence data | ✓ Available |
| HCPCS J-code billing crosswalk | — Not published for this NDC Most self-administered / retail products have no J-code — that is normal. |
| Medicaid utilization (CMS SDUD) | — Not published for this NDC CMS reports utilization only for NDCs with Medicaid claims above its privacy threshold. |
Questions about this listing
Why is there no price listed?
Is the NDC printed on the package the same as the 11-digit billing NDC?
What do the three segments of this NDC mean?
Is this package still being marketed?
Does this product come in other package sizes?
Who lists this product with the FDA?
Do I need a prescription for this product?
Where does this data come from?
📄 Full prescribing information FDA SPL
🎯 Indications and Usage ▾
INDICATIONS AND USAGE Primidone tablets used alone or concomitantly with other anticonvulsants, are indicated in the control of grand mal, psychomotor, and focal epileptic seizures. It may control grand mal seizures refractory to other anticonvulsant therapy.
⏱️ Dosage and Administration ▾
DOSAGE AND ADMINISTRATION Dosage Usual Dosage Patients 8 years of age and older who have received no previous treatment may be started on primidone tablets according to the following regimen using either 50 mg or scored 250 mg primidone tablets: Days 1 to 3: 100 to 125 mg at bedtime. Days 4 to 6: 100 to 125 mg twice a day. Days 7 to 9: 100 to 125 mg three times a day.
Day 10 to maintenance: 250 mg three times a day. For most adults and children 8 years of age and over, the usual maintenance dosage is three to four 250 mg primidone tablets in divided doses (250 mg three times a day or four times a day). If required, an increase to five or six 250 mg tablets daily may be made, but daily doses should not exceed 500 mg four times a day.
Dosage should be individualized to provide maximum benefit. In some cases, serum blood level determinations of primidone may be necessary for optimal dosage adjustment. The clinically effective serum level for primidone is between 5 to 12 mcg/mL.
Patients Already Receiving Other Anticonvulsants Primidone tablets should be started at 100 to 125 mg at bedtime and gradually increased to maintenance level as the other drug is gradually decreased. This regimen should be continued until satisfactory dosage level is achieved for the combination, or the other medication is completely withdrawn. When therapy with primidone tablets alone is the objective, the transition from concomitant therapy should not be completed in less than two weeks.
Pediatric Dosage For children under 8 years of age, the following regimen may be used: Days 1 to 3: 50 mg at bedtime. Days 4 to 6: 50 mg twice a day. Days 7 to 9: 100 mg twice a day.
Day 10 to maintenance: 125 mg three times a day to 250 mg three times a day. For children under 8 years of age, the usual maintenance dosage is 125 to 250 mg three times daily or, 10 to 25 mg/kg/day in divided doses. 1
⛔ Contraindications ▾
CONTRAINDICATIONS Primidone is contraindicated in: 1) patients with porphyria and 2) patients who are hypersensitive to phenobarbital (see CLINICAL PHARMACOLOGY ).
⚠️ Warnings ▾
WARNINGS The abrupt withdrawal of antiepileptic medication may precipitate status epilepticus. The therapeutic efficacy of a dosage regimen takes several weeks before it can be assessed. Suicidal Behavior and Ideation Antiepileptic drugs (AEDs), including primidone, increase the risk of suicidal thoughts or behavior in patients taking these drugs for any indication.
Patients treated with any AED for any indication should be monitored for the emergence or worsening of depression, suicidal thoughts or behavior, and/or any unusual changes in mood or behavior. Pooled analyses of 199 placebo-controlled clinical trials (mono- and adjunctive therapy) of 11 different AEDs showed that patients randomized to one of the AEDs had approximately twice the risk (adjusted Relative Risk 1.8, 95% CI:1.2, 2.7) of suicidal thinking or behavior compared to patients randomized to placebo. In these trials, which had a median treatment duration of 12 weeks, the estimated incidence rate of suicidal behavior or ideation among 27,863 AED-treated patients was 0.43%, compared to 0.24% among 16,029 placebo-treated patients, representing an increase of approximately one case of suicidal thinking or behavior for every 530 patients treated.
There were four suicides in drug-treated patients in the trials and none in placebo-treated patients, but the number is too small to allow any conclusion about drug effect on suicide. The increased risk of suicidal thoughts or behavior with AEDs was observed as early as one week after starting drug treatment with AEDs and persisted for the duration of treatment assessed. Because most trials included in the analysis did not extend beyond 24 weeks, the risk of suicidal thoughts or behavior beyond 24 weeks could not be assessed.
The risk of suicidal thoughts or behavior was generally consistent among drugs in the data analyzed. The finding of increased risk with AEDs of varying mechanisms of action and across a range of indications suggests that the risk applies to all AEDs used for any indication. The risk did not vary substantially by age (5 to 100 years) in the clinical trials analyzed.
Table 1 shows absolute and relative risk by indication for all evaluated AEDs. The relative risk for suicidal thoughts or behavior was higher in clinical trials for epilepsy than in clinical trials for psychiatric or other conditions, but the absolute risk differences were similar for the epilepsy and psychiatric indications. Anyone considering prescribing primidone or any other AED must balance the risk of suicidal thoughts or behavior with the risk of untreated illness.
Epilepsy and many other illnesses for which AEDs are prescribed are themselves associated with morbidity and mortality and an increased risk of suicidal thoughts and behavior. Should suicidal thoughts and behavior emerge during treatment, the prescriber needs to consider whether the emergence of these symptoms in any given patient may be related to the illness being treated. Patients, their caregivers, and families should be informed that AEDs increase the risk of suicidal thoughts and behavior and should be advised of the need to be alert for the emergence or worsening of the signs and symptoms of depression, any unusual changes in mood or behavior, or the emergence of suicidal thoughts, behavior, or thoughts about self-harm.
Behaviors of concern should be reported immediately to healthcare providers. 1 Pregnancy To provide information regarding the effects of in utero exposure to primidone, physicians are advised to recommend that pregnant patients taking primidone enroll in the North American Antiepileptic Drug (NAAED) Pregnancy Registry. This can be done by calling the toll-free number 1-888-233-2334, and must be done by patients themselves.
Information on the registry can also be found at the website http://www.aedpregnancyregistry.org/. The effects of primidone in human pregnancy and nursing infants are unknown. Recent reports suggest an association between the use o…
🤒 Adverse Reactions ▾
ADVERSE REACTIONS The most frequently occurring early side effects are ataxia and vertigo. These tend to disappear with continued therapy, or with reduction of initial dosage. Occasionally, the following have been reported: nausea, anorexia, vomiting, fatigue, hyperirritability, emotional disturbances, sexual impotency, diplopia, nystagmus, drowsiness, and morbilliform skin eruptions.
Granulocytopenia, agranulocytosis, and red-cell hypoplasia and aplasia, have been reported rarely. These and, occasionally, other persistent or severe side effects may necessitate withdrawal of the drug. Megaloblastic anemia may occur as a rare idiosyncrasy to primidone and to other anticonvulsants.
The anemia responds to folic acid without necessity of discontinuing medication. To report SUSPECTED ADVERSE REACTIONS, contact AvKARE at 1-855-361-3993 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.
🤰 Pregnancy ▾
Pregnancy To provide information regarding the effects of in utero exposure to primidone, physicians are advised to recommend that pregnant patients taking primidone enroll in the North American Antiepileptic Drug (NAAED) Pregnancy Registry. This can be done by calling the toll-free number 1-888-233-2334, and must be done by patients themselves. Information on the registry can also be found at the website http://www.aedpregnancyregistry.org/.
The effects of primidone in human pregnancy and nursing infants are unknown. Recent reports suggest an association between the use of anticonvulsant drugs by women with epilepsy and an elevated incidence of birth defects in children born to these women. Data are more extensive with respect to diphenylhydantoin and phenobarbital, but these are also the most commonly prescribed anticonvulsants; less systematic or anecdotal reports suggest a possible similar association with the use of all known anticonvulsant drugs.
The reports suggesting an elevated incidence of birth defects in children of drug-treated epileptic women cannot be regarded as adequate to prove a definite cause-and-effect relationship. There are intrinsic methodologic problems in obtaining adequate data on drug teratogenicity in humans, the possibility also exists that other factors leading to birth defects, e.g., genetic factors or the epileptic condition itself, may be more important than drug therapy. The great majority of mothers on anticonvulsant medication deliver normal infants.
It is important to note that anticonvulsant drugs should not be discontinued in patients in whom the drug is administered to prevent major seizures because of the strong possibility of precipitating status epilepticus with attendant hypoxia and threat to life. In individual cases where the severity and frequency of the seizure disorders are such that the removal of medication does not pose a serious threat to the patient, discontinuation of the drug may be considered prior to and during pregnancy, although it cannot be said with any confidence that even minor seizures do not pose some hazard to the developing embryo or fetus.
The prescribing physician will wish to weigh these considerations in treating or counseling epileptic women of childbearing potential. Neonatal hemorrhage, with a coagulation defect resembling vitamin K deficiency, has been described in newborns whose mothers were taking primidone and other anticonvulsants. Pregnant women under anticonvulsant therapy should receive prophylactic vitamin K1 therapy for one month prior to, and during, delivery.
🧬 Clinical Pharmacology ▾
CLINICAL PHARMACOLOGY Primidone raises electro- or chemoshock seizure thresholds or alters seizure patterns in experimental animals. The mechanisms(s) of primidone’s antiepileptic action is not known. Primidone per se has anticonvulsant activity as do its two metabolites, phenobarbital and phenylethylmalonamide (PEMA). In addition to its anticonvulsant activity, PEMA potentiates the anticonvulsant activity of phenobarbital in experimental animals.
📦 How Supplied / Storage and Handling ▾
HOW SUPPLIED Primidone Tablets, USP, 50 mg are supplied as white, round, flat-faced, bevel-edged tablets, debossed “AN” above “44” on one side and cut-bisected on the other side. They are available as follows: Bottles of 100: NDC 42291-509-01 Bottles of 500: NDC 42291-509-50 Primidone Tablets, USP, 250 mg are supplied as white, round, flat-faced, bevel-edged tablets, debossed “AN” bisect “545” on one side and plain on the other side. They are available as follows: Bottles of 100: NDC 42291-511-01 Bottles of 500: NDC 42291-511-50 Store at 20°C to 25°C (68°F to 77°F); excursions permitted to 15°C-30°C (59°F- 86°F). [See USP Controlled Room Temperature].
Dispense contents with a child-resistant closure (as required) and in a tight, light-resistant container as defined in the USP. KEEP THIS AND ALL MEDICATION OUT OF REACH OF CHILDREN. Manufactured for: AvKARE Pulaski, TN 38478 Mfg.
Rev. 12-2021-03 AV 01/23
📦 Storage and Handling ▾
Store at 20°C to 25°C (68°F to 77°F); excursions permitted to 15°C-30°C (59°F- 86°F). [See USP Controlled Room Temperature]. Dispense contents with a child-resistant closure (as required) and in a tight, light-resistant container as defined in the USP. KEEP THIS AND ALL MEDICATION OUT OF REACH OF CHILDREN. Manufactured for: AvKARE Pulaski, TN 38478 Mfg. Rev. 12-2021-03 AV 01/23
📋 Description ▾
DESCRIPTION Primidone, USP is a white, crystalline, highly stable substance, M.P. 279-284° C. It is poorly soluble in water (60 mg per 100 mL at 37° C) and in most organic solvents.
It possesses no acidic properties, in contrast to its barbiturate analog. Chemical name: 5-ethyldihydro-5-phenyl-4,6 (1H, 5H)-pyrimidinedione. Structural formula: Primidone tablets USP, 50 mg and 250 mg contain the following inactive ingredients: corn starch, lactose monohydrate, magnesium stearate, methyl cellulose, microcrystalline cellulose, sodium lauryl sulfate, sodium starch glycolate.
1
💬 Information for Patients ▾
Suicidal Thoughts and Behavior Patients, their caregivers, and families should be counseled that AEDs, including primidone, may increase the risk of suicidal thoughts and behavior and should be advised of the need to be alert for the emergence or worsening of symptoms of depression, any unusual changes in mood or behavior, or the emergence of suicidal thoughts, behavior, or thoughts about self-harm. Behaviors of concern should be reported immediately to healthcare providers. Pregnancy Patients should be encouraged to enroll in the NAAED Pregnancy Registry if they become pregnant.
This registry is collecting information about the safety of antiepileptic drugs during pregnancy. To enroll, patients can call the toll-free number 1-888-233-2334 (see WARNINGS, Pregnancy). Please refer to the Primidone Medication Guide for more information.
💬 Medication Guide ▾
SPL MEDGUIDE SECTION What is the most important information I should know about primidone? Like other antiepileptic drugs, primidone may cause suicidal thoughts or actions in a very small number of people, about 1 in 500. Call a healthcare provider right away if you have any of these symptoms, especially if they are new, worse, or worry you: thoughts about suicide or dying attempts to commit suicide new or worsening depression new or worsening anxiety feeling agitated or restless panic attacks trouble sleeping (insomnia) new or worsening irritability acting aggressive, being angry, or violent acting on dangerous impulses an extreme increase in activity and talking (mania) other unusual changes in behavior or mood Do not stop taking primidone without first talking to a healthcare provider.
Stopping primidone suddenly can cause serious problems. Stopping a seizure medicine suddenly in a patient who has epilepsy can cause seizures that will not stop (status epilepticus). Suicidal thoughts or actions can be caused by things other than medicines.
If you have suicidal thoughts or actions, your healthcare provider may check for other causes. How can I watch for early symptoms of suicidal thoughts and actions? Pay attention to any changes, especially sudden changes, in mood, behaviors, thoughts, or feelings.
Keep all follow-up visits with your healthcare provider as scheduled. Call your healthcare provider between visits as needed, especially if you are worried about symptoms. What is primidone?
Primidone is a prescription medicine used alone or with other medicines to treat people with: generalized tonic-clonic (grand mal) seizures complex partial (psychomotor) seizures partial (focal) epileptic seizures Who should not take primidone? Do not take primidone if you: have a genetic disorder called porphyria are allergic to phenobarbital What should I tell my healthcare provider before taking primidone? Before you take primidone, tell your healthcare provider if you: have or have had depression, mood problems, or suicidal thoughts or behavior have any other medical conditions are pregnant or planning to become pregnant.
Primidone may harm your unborn baby. Tell your healthcare provider right away if you become pregnant while taking primidone. You and your healthcare provider will decide if you should take primidone while you are pregnant.
If you become pregnant while taking primidone, talk to your healthcare provider about registering with the North American Antiepileptic Drug (NAAED) Pregnancy Registry. You can enroll in this registry by calling 1-888-233-2334. The purpose of this registry is to collect information about the safety of antiepileptic drugs during pregnancy. are breastfeeding or plan to breastfeed.
Primidone can pass into breast milk. Talk to your healthcare provider about the best way to feed your baby if you take primidone. Tell your healthcare provider about all the medicines you take, including prescription and non-prescription medicines, vitamins, and herbal supplements.
Taking primidone with certain other medicines can cause side effects or affect how well they work. Do not start or stop other medicines without talking to your healthcare provider. Know the medicines you take.
Keep a list of them and show it to your healthcare provider and pharmacist each time you get a new medicine. How should I take primidone tablets? Take primidone tablets exactly as prescribed.
Your healthcare provider will tell you how much primidone tablets to take and when to take it. Your healthcare provider may change your dose. Do not change your dose without talking to your healthcare provider.
Do not stop taking primidone tablets without first talking to your healthcare provider. Stopping primidone tablets suddenly can cause serious problems. If you take too much primidone, call your healthcare provider or local Poison Control Center right away.
What should I avoid while taking primidone? Primidone can make you sleepy or dizzy. Do not drin…