Primidone, Oral

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KEY POINTS

• This medicine is taken by mouth control and reduce seizures. Take it exactly as directed. Carry some form of identification stating that you have seizures and are taking an antiseizure medicine.
• This medicine may increase suicidal thoughts or actions in some people.
• This medicine may make hormonal birth control less effective.
• This medicine may cause unwanted side effects. Tell your healthcare provider if you have any side effects that are serious, continue, or get worse.
• Tell all healthcare providers who treat you about all the prescription medicines, nonprescription medicines, supplements, natural remedies, and vitamins that you take.

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What are other names for this medicine?

Type of medicine: antiseizure; barbiturate

Generic and brand names: primidone, oral; Mysoline

What is this medicine used for?

This medicine is taken by mouth to control and reduce seizures caused by epilepsy. It may be used alone or with other medicines.

This medicine may be used to treat other conditions as determined by your healthcare provider.

What should my healthcare provider know before I take this medicine?

Before taking this medicine, tell your healthcare provider if you have ever had:

• An allergy to any medicines
• Depression or thoughts of suicide
• Kidney or liver disease
• Lung disease
• Porphyria (nerve pain or sensitivity to sunlight)

This medicine may make hormonal birth control less effective. If you need birth control, talk to your healthcare provider about methods that are effective while you are taking this medicine.

Females of childbearing age: This medicine is not usually given to pregnant women because it can harm the baby. If you are pregnant, tell your healthcare provider. Do not become pregnant during treatment with this medicine. If you become pregnant, contact your healthcare provider right away. You and your healthcare provider should decide if you should continue taking this medicine while you are pregnant. Do not breast-feed while you are receiving this medicine.

How do I use it?

Read the Medication Guide that comes in the medicine package when you start taking this medicine and each time you get a refill.

Check the label on the medicine for directions about your specific dose. Take this medicine exactly as your healthcare provider prescribes, in regularly spaced doses every day. Your healthcare provider may adjust your dosage, depending on your response and any side effects you may have. Be sure you know exactly how much to take each day and when to take each dose. Do not stop taking this medicine without your healthcare provider's approval. You may have to reduce your dosage gradually.

You may take this medicine with or without food. Taking it with meals may lessen the chance the drug will upset your stomach. Take it with a full glass of water.

What if I miss a dose?

If you miss a dose, take it as soon as you remember unless it is almost time for the next scheduled dose. In that case, skip the missed dose and take the next one as directed. Do not take double doses. If you are not sure of what to do if you miss a dose, or if you miss more than one dose, contact your healthcare provider.

What if I overdose?

If you or anyone else has intentionally taken too much of this medicine, call 911 or go to the emergency room right away. If you pass out, have seizures, weakness or confusion, or have trouble breathing, call 911. If you think that you or anyone else may have taken too much of this medicine, call the poison control center. Do this even if there are no signs of discomfort or poisoning. The poison control center number is 800-222-1222.

Symptoms of an acute overdose may include: dizziness, drowsiness, lack of coordination, trouble walking, confusion, cold skin, fever, lightheadedness, fainting, slowed breathing, nausea, vomiting, slurred speech, coma.

What should I watch out for?

Antiseizure medicines may increase suicidal thoughts or actions in some people. Call your healthcare provider right away if you have new or worsening depression, any unusual changes in mood or behavior, or new or increased thoughts of suicide.

Your healthcare provider will check your progress regularly and adjust your dosage. You will need blood tests regularly to see how this medicine affects you. Keep all appointments.

You may get infections more easily while taking this medicine. Contact your healthcare provider right away if you have any signs of infection such as fever, chills, or sore throat. Also, contact your healthcare provider if you have unusual bruising or bleeding or unusual tiredness or weakness.

This medicine may make you drowsy or dizzy. Do not drive or operate machinery unless you are fully alert.

This medicine increases the effects of alcohol and other drugs that slow down your nervous system. Do not drink alcohol or take other medicines unless your healthcare provider approves.

If you need emergency care, surgery, lab tests, or dental work, tell the healthcare provider or dentist you are taking this medicine. Wear some form of identification a Medic Alert bracelet stating that you take this medicine for epilepsy. The ID tells emergency healthcare providers that you may need special care.

What are the possible side effects?

Along with its needed effects, your medicine may cause some unwanted side effects. Some side effects may be very serious. Some side effects may go away as your body adjusts to the medicine. Tell your healthcare provider if you have any side effects that continue or get worse.

Life-threatening (Report these to your healthcare provider right away. If you cannot reach your healthcare provider right away, get emergency medical care or call 911 for help.): Allergic reaction (hives; itching; rash; trouble breathing; tightness in your chest; swelling of your lips, tongue, and throat).

Serious (Report these to your healthcare provider right away.): Unusual excitement or restlessness; wheezing; vision problems; depression or thoughts of suicide; unusual changes in mood or behavior; trouble concentrating; confusion; worsening of seizures; unexplained fever or sore throat; cough; swollen glands; yellowing of the skin or eyes; dark urine; unusual bruising or bleeding; unusual tiredness or weakness; trouble standing or walking; rash, blistering or peeling skin, or any skin problem; mouth sores; severe dizziness or fainting.

Other: Drowsiness, mild dizziness, loss of appetite, nausea, vomiting, change in sexual ability or desire.

What products might interact with this medicine?

When you take this medicine with other medicines, it can change the way this or any of the other medicines work. Nonprescription medicines, vitamins, natural remedies, and certain foods may also interact. Using these products together might cause harmful side effects. Talk to your healthcare provider if you are taking:

• Alpha blockers such as alfuzosin (Uroxatral), doxazosin (Cardura), and silodosin (Rapaflo)
• Antianxiety medicines such as alprazolam (Xanax), buspirone, clonazepam (Klonopin), clorazepate (Gen-Xene, Tranxene), diazepam (Valium), lorazepam (Ativan), and oxazepam
• Antibiotics such as bedaquiline (Sirturo), clarithromycin (Biaxin), erythromycin (E.E.S., Ery-Tab, Erythrocin), rifampin (Rifadin), and telithromycin (Ketek)
• Antidepressants such as amitriptyline, citalopram (Celexa), duloxetine (Cymbalta), escitalopram (Lexapro), fluoxetine (Prozac), fluvoxamine (Luvox), imipramine (Tofranil), nefazodone, nortriptyline (Pamelor), sertraline (Zoloft), trazodone, venlafaxine (Effexor), vilazodone (Viibryd), and vortioxetine (Trintellix)
• Antifungal medicines such as griseofulvin (Grifulvin V, Gris-PEG), isavuconazonium (Cresemba), itraconazole (Sporanox), ketoconazole (Nizoral), and voriconazole (Vfend)
• Antihistamines such as azelastine (Astelin, Astepro), chlorpheniramine (Chlor-Trimeton), diphenhydramine (Benadryl), and hydroxyzine (Vistaril)
• Antipsychotic medicines such as aripiprazole (Abilify), cariprazine (Vraylar), chlorpromazine, clozapine (Clozaril, FazaClo), haloperidol (Haldol), lurasidone (Latuda), olanzapine (Zyprexa), quetiapine (Seroquel), risperidone (Risperdal), thioridazine, trifluoperazine, and ziprasidone (Geodon)
• Antiseizure medicines such as carbamazepine (Carbatrol, Epitol, Equetro, Tegretol), clobazam (Onfi), eslicarbazepine (Aptiom), ethosuximide (Zarontin), fosphenytoin (Cerebyx), gabapentin (Neurontin), lamotrigine (Lamictal), levetiracetam (Keppra), methsuximide (Celontin), oxcarbazepine (Trileptal), phenobarbital, phenytoin (Dilantin, Phenytek), rufinamide (Banzel), topiramate (Qudexy, Topamax, Trokendi), valproic acid (Depacon, Depakene, Depakote), vigabatrin (Sabril), and zonisamide (Zonegran)
• Antiviral medicines such as daclatasvir (Daklinza), elbasvir/grazoprevir (Zepatier), ledipasvir/sofosbuvir (Harvoni), ombitasvir/paritaprevir/ritonavir (Technivie), ombitasvir/paritaprevir/ritonavir/dasabuvir (Viekira), simeprevir (Olysio), and sofosbuvir (Sovaldi)
• Apremilast (Otezla)
• Bupropion (Aplenzin, Forfivo, Wellbutrin, Buproban, Zyban)
• Cancer medicines such as abiraterone (Zytiga), axitinib (Inlyta), bortezomib (Velcade), bosutinib (Bosulif), cabozantinib (Cometriq), ceritinib (Zykadia), cobimetinib (Cotellic), crizotinib (Xalkori), dabrafenib (Tafinlar), dasatinib (Sprycel), docetaxel (Docefrez, Taxotere), doxorubicin (Doxil), enzalutamide (Xtandi), erlotinib (Tarceva), etoposide, gefitinib (Iressa), ibrutinib (Imbruvica), ifosfamide (Ifex), imatinib (Gleevec), irinotecan (Camptosar), ixazomib (Ninlaro), lapatinib (Tykerb), nilotinib (Tasigna), nilutamide (Nilandron), olaparib (Lynparza), pazopanib (Votrient), ponatinib (Iclusig), romidepsin (Istodax), sorafenib (Nexavar), vandetanib (Caprelsa), vemurafenib (Zelboraf), and vincristine (Marqibo)
• Cholesterol-lowering medicines such as atorvastatin (Lipitor), lomitapide (Juxtapid), lovastatin (Altoprev), and simvastatin (Zocor)
• Cimetidine (Tagamet)
• Corticosteroids such as betamethasone, cortisone, dexamethasone, fludrocortisone, hydrocortisone (A-Hydrocort, Cortef), methylprednisolone (Medrol, Solu-Medrol), prednisolone (Omnipred, Orapred, Prelone), prednisone (Prednisone Intensol), and triamcinolone (Aristospan, Kenalog)
• Cystic fibrosis medicines such as ivacaftor (Kalydeco) and lumacaftor/ivacaftor (Orkambi)
• Diabetes medicines such as chlorpropamide, glimepiride (Amaryl), glipizide (Glucotrol), glyburide (Glynase), linagliptin (Tradjenta), nateglinide (Starlix), pioglitazone (Actos), repaglinide (Prandin), rosiglitazone (Avandia), saxagliptin (Onglyza), and tolbutamide
• Doxepin (Silenor)
• Eliglustat (Cerdelga)
• Exemestane (Aromasin)
• Heart medicines such as amiodarone (Cordarone, Pacerone), diltiazem (Cardizem, Cartia, Tiazac), disopyramide (Norpace), dronedarone (Multaq), felodipine, isradipine (DynaCirc), ivabradine (Corlanor), losartan (Cozaar), nicardipine (Cardene), nifedipine (Adalat CC, Procardia), nisoldipine (Sular), quinidine, ranolazine (Ranexa), and verapamil (Calan, Covera, Verelan)
• HIV medicines such as atazanavir (Reyataz), darunavir (Prezista), delavirdine (Rescriptor), dolutegravir (Tivicay), efavirenz (Sustiva), elvitegravir/cobicistat/emtricitabine/tenofovir (Stribild), etravirine (Intelence), fosamprenavir (Lexiva), indinavir (Crixivan), lopinavir/ritonavir (Kaletra), nelfinavir (Viracept), nevirapine (Viramune), rilpivirine (Edurant), ritonavir (Norvir), and saquinavir (Invirase)
• Hormonal birth control pills, implants, shots, patches, vaginal rings, and IUDs, and hormones such as conjugated estrogens (Premarin), estradiol (Climara, Estrace, Estraderm, Vivelle), medroxyprogesterone (Depo-Provera, Provera), and norethindrone (Aygestin, Micronor)
• Immunosuppressants such as cyclosporine (Gengraf, Neoral, Sandimmune), sirolimus (Rapamune), and tacrolimus (Astagraf, Prograf, Protopic)
• Macitentan (Opsumit)
• Malaria medicines such as artemether/lumefantrine (Coartem), chloroquine, mefloquine, primaquine, and quinine
• MAO inhibitors such as isocarboxazid (Marplan), phenelzine (Nardil), selegiline (Eldepryl, Emsam, Zelapar), and tranylcypromine (Parnate) (Do not take this medicine and an MAO inhibitor within 14 days of each other.)
• Medicines to treat breathing or lung problems such as aminophylline, montelukast (Singular), roflumilast (Daliresp), theophylline, and zafirlukast (Accolate)
• Medicines to treat low sodium levels such as conivaptan (Vaprisol) and tolvaptan (Samsca)
• Medicines to treat or prevent blood clots such as apixaban (Eliquis), cilostazol (Pletal), dabigatran (Pradaxa), edoxaban (Savaysa), rivaroxaban (Xarelto), ticagrelor (Brilinta), and warfarin (Coumadin)
• Mifepristone (Korlym, Mifeprex)
• Muscle relaxants such as baclofen (Gablofen, Lioresal), carisoprodol (Soma), cyclobenzaprine (Amrix), methocarbamol (Robaxin), and tizanidine (Zanaflex)
• Natural remedies such as ginkgo biloba, gotu kola, kava, SAMe, St. John's wort, and valerian
• Nausea medicines such as aprepitant (Emend), ondansetron (Zofran), prochlorperazine (Compro), promethazine, and rolapitant (Varubi)
• Nintedanib (Ofev)
• Pain medicines such as celecoxib (Celebrex), codeine, diclofenac (Cambia, Voltaren, Zipsor), fentanyl (Abstral, Actiq, Duragesic, Fentora, Sublimaze), hydrocodone (Hysingla, Zohydro), hydromorphone (Dilaudid, Exalgo), meloxicam (Mobic), meperidine (Demerol), methadone (Dolophine, Methadose), morphine (Kadian, MS Contin), oxycodone (OxyContin, Roxicodone), pentazocine (Talwin), piroxicam (Feldene), and tramadol (ConZip, Ultram)
• Paroxetine (Brisdelle, Paxil, Pexeva)
• Praziquantel (Biltricide)
• Sleeping pills such as butabarbital (Butisol), eszopiclone (Lunesta), flurazepam, suvorexant (Belsomra), temazepam (Restoril), triazolam (Halcion), zaleplon (Sonata), and zolpidem (Ambien, Edluar, Intermezzo)
• Stimulants such as armodafinil (Nuvigil), dexmethylphenidate (Focalin), methylphenidate (Concerta, Daytrana, Metadate, Ritalin), and modafinil (Provigil)
• Sulfa antibiotics such as sulfadiazine, sulfamethoxazole/trimethoprim (Bactrim, Septra), and sulfasalazine (Azulfidine)
• Tadalafil (Adcirca, Cialis)
• Tofacitinib (Xeljanz)

Do not drink alcohol unless your healthcare provider approves.

If you are not sure if your medicines might interact, ask your pharmacist or healthcare provider. Keep a list of all your medicines with you. List all the prescription medicines, nonprescription medicines, supplements, natural remedies, and vitamins that you take. Be sure that you tell all healthcare providers who treat you about all the products you are taking.

How should I store this medicine?

Store this medicine at room temperature. Keep the container tightly closed. Protect it from heat, high humidity, and bright light.

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This advisory includes selected information only and may not include all side effects of this medicine or interactions with other medicines. Ask your healthcare provider or pharmacist for more information or if you have any questions.

Ask your pharmacist for the best way to dispose of outdated medicine or medicine you have not used. Do not throw medicine in the trash.

Keep all medicines out of the reach of children.

Do not share medicines with other people.