Phenobarbital, Oral/Injection

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KEY POINTS

• This medicine is used to relieve tension or anxiety, to help you sleep, or to prevent seizures. Take it exactly as directed.
• This medicine will make you drowsy. Do not drive or operate machinery until you are fully alert.
• This medicine may cause unwanted side effects. Tell your healthcare provider if you have any side effects that are serious, continue, or get worse.
• This medicine may interact with many other medicines. 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: barbiturate

Generic and brand names: phenobarbital, oral; phenobarbital, injection

What is this medicine used for?

This medicine is used to relieve tension or anxiety, to help you sleep, or to prevent seizures.

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 allergic reaction to any medicine
• Anemia or another blood disease
• Depression or thoughts of suicide
• Diabetes
• Heart disease
• Liver or kidney disease
• Lung disease
• Porphyria (chemical imbalance that can affect the nerves and skin)
• Problems with alcohol or substance abuse
• Thyroid problems
• Uncontrolled pain

Females of childbearing age: Tell your healthcare provider if you are pregnant or become pregnant while taking this medicine. This medicine is not usually taken during pregnancy because it may harm the baby. Do not become pregnant during treatment with this medicine. If you become pregnant, contact your healthcare provider right away. This medicine may make birth control pills less effective. If you need birth control, talk to your healthcare provider about methods that are effective while you are taking this medicine. Do not breast-feed while you are taking this medicine.

How do I use it?

Check the label on the medicine for directions about your specific dose. Take this medicine exactly as your healthcare provider prescribes. Do not take more of it or take it longer than prescribed. Taking too much may be habit-forming or you may overdose.

Do not stop taking this medicine without your healthcare provider's approval if you have taken it for a long time. You may have to reduce your dosage gradually to avoid withdrawal symptoms. Talk with your healthcare provider about this.

Check with your healthcare provider before using this medicine in children.

For this medicine to prevent seizures, you must take it regularly. If you are taking this medicine to help you sleep, take it 30 to 60 minutes before bedtime.

This medicine may also be given by your healthcare provider as an injection (shot) in the muscle or by IV infusion (slow drip through a needle into a large vein) while you are in the hospital or clinic.

If you have the liquid form of this medicine, use the measuring spoon, cup, dropper, or oral syringe that comes with the medicine, or ask your pharmacist for one. Do not use a kitchen spoon because the dose may not be correct.

If you take this medicine for a long time, you may need a vitamin D supplement. Ask your healthcare provider about this.

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 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: slow or shallow breathing, blurred vision, extreme drowsiness, decreased urination, lightheadedness, fainting, fast heartbeat, feeling cold, slurred speech, unsteadiness, uncontrolled eye movements, coma.

What should I watch out for?

Do not stop taking this medicine without your healthcare provider's approval, especially if you have taken it for more than 2 weeks. You may have to reduce your dosage gradually to prevent serious side effects. Do not start or stop taking any other medicine without your healthcare provider’s advice.

If you take this medicine for a long time, you may need blood tests to find out how this medicine affects you. Keep all appointments for these tests.

This medicine will make you drowsy. Do not drive or operate machinery until you are fully alert.

This medicine may cause memory loss or amnesia. You may not know what you are doing for several hours after taking the medicine, including driving in your sleep. If you have memory problems while taking this medicine, contact your healthcare provider right away.

You may feel dizzy or faint when you get up quickly after sitting or lying down. Getting up slowly may help.

This medicine may increase 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.

This medicine may produce excitement rather than calming in some people. If this happens, contact your healthcare provider.

If you are taking this medicine to help you sleep, contact your healthcare provider if your insomnia does not improve in 7 to 10 days or if it gets worse.

This medicine is a controlled substance. It is illegal to give this medicine to anyone else.

Adults over the age of 65 may be at greater risk for side effects. Talk with your healthcare provider about this.

If you need emergency care, surgery, lab tests, or dental work, tell the healthcare provider or dentist that you are taking this medicine.

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.): Yellowing of your skin or eyes, dark urine, severe stomach pain, severe nausea or vomiting, fever, hallucinations (seeing or hearing things that are not there), trouble breathing, severe dizziness or fainting, new or worsening depression, confusion, slow heartbeat, unusual thoughts or behavior, worsening trouble sleeping, unusual excitement or agitation, memory problems, trouble walking, unusual tiredness or weakness; severe drowsiness; severe skin redness, peeling, or blisters; burning, pain, redness, or swelling at the injection site.

Other: Dizziness, mild drowsiness, headache, nervousness, nightmares, mild nausea, constipation.

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:

• Acetaminophen and medicines that contain acetaminophen
• Alfuzosin (Uroxatral)
• Antianxiety medicines such as alprazolam (Xanax), clonazepam (Klonopin), clorazepate (Gen-Xene, Tranxene), diazepam (Valium), lorazepam (Ativan), and oxazepam
• Antiarrhythmic medicines (to treat irregular heartbeat) such as amiodarone (Cordarone, Pacerone), disopyramide (Norpace), dronedarone (Multaq), propafenone (Rythmol), and quinidine
• Antibiotics such as bedaquiline (Sirturo), chloramphenicol, clarithromycin (Biaxin), doxycycline (Doryx, Monodox, Vibramycin), isoniazid, metronidazole, rifabutin (Mycobutin), rifampin (Rifadin), rifapentine (Priftin), sulfadiazine, sulfamethoxazole/trimethoprim (Bactrim, Septra), and telithromycin (Ketek)
• Antidepressants such as amitriptyline, amoxapine, citalopram (Celexa), clomipramine (Anafranil), desipramine (Norpramin), desvenlafaxine (Pristiq), duloxetine (Cymbalta), escitalopram (Lexapro), fluoxetine (Prozac), fluvoxamine (Luvox), imipramine (Tofranil), nefazodone, nortriptyline (Pamelor), protriptyline (Vivactil), sertraline (Zoloft), trimipramine (Surmontil), and venlafaxine (Effexor)
• Antifungal medicines such as fluconazole (Diflucan), griseofulvin (Grifulvin V, Gris-PEG), itraconazole (Sporanox), and voriconazole (Vfend)
• Antihistamines such as chlorpheniramine (Chlor-Trimeton) and diphenhydramine (Benadryl)
• Antipsychotic medicines such as aripiprazole (Abilify), asenapine (Saphris), chlorpromazine, clozapine (Clozaril, FazaClo), fluphenazine, haloperidol (Haldol), iloperidone (Fanapt), olanzapine (Zyprexa), paliperidone (Invega), pimozide (Orap), quetiapine (Seroquel), risperidone (Risperdal), thioridazine, trifluoperazine, and ziprasidone (Geodon)
• Antiseizure medicines such as carbamazepine (Carbatrol, Epitol, Equetro, Tegretol), ethotoin (Peganone), felbamate (Felbatol), lamotrigine (Lamictal), phenytoin (Dilantin, Phenytek), topiramate (Qudexy, Topamax, Trokendi), and valproic acid (Depacon, Depakene, Depakote)
• Antiviral medicines such as daclatasvir (Daklinza), elbasvir/grazoprevir (Zepatier), ledipasvir/sofosbuvir (Harvoni), simeprevir (Olysio), and sofosbuvir (Sovaldi)
• Apremilast (Otezla)
• Beta blockers such as acebutolol (Sectral), atenolol (Tenormin), bisoprolol (Zebeta), carvedilol (Coreg), labetalol (Trandate), metoprolol (Lopressor, Toprol), nadolol (Corgard), nebivolol (Bystolic), pindolol, and sotalol (Betapace, Sorine)
• Blood pressure medicines such as hydralazine, methyldopa, minoxidil, and reserpine
• Bupropion (Aplenzin, Forfivo, Wellbutrin, Buproban, Zyban)
• Calcium channel blockers such as diltiazem (Cardizem, Cartia, Tiazac), felodipine, isradipine (DynaCirc), nicardipine (Cardene), nifedipine (Adalat CC, Procardia), nimodipine (Nymalize), nisoldipine (Sular), and verapamil (Calan, Covera, Verelan)
• Cancer medicines such as abiraterone (Zytiga), axitinib (Inlyta), bortezomib (Velcade), bosutinib (Bosulif), cabozantinib (Cometriq), ceritinib (Zykadia), cobimetinib (Cotellic), crizotinib (Xalkori), dabrafenib (Tafinlar), dasatinib (Sprycel), enzalutamide (Xtandi), erlotinib (Tarceva), ibrutinib (Imbruvica), idelalisib (Zydelig), imatinib (Gleevec), ixazomib (Ninlaro), lapatinib (Tykerb), nilotinib (Tasigna), olaparib (Lynparza), osimertinib (Tagrisso), palbociclib (Ibrance), panobinostat (Farydak), pazopanib (Votrient), ponatinib (Iclusig), regorafenib (Stivarga), sonidegib (Odomzo), sorafenib (Nexavar), sunitinib (Sutent), vandetanib (Caprelsa), and vemurafenib (Zelboraf)
• Cholesterol-lowering medicines such as atorvastatin (Lipitor), cholestyramine (Prevalite), gemfibrozil (Lopid), and lovastatin (Altoprev)
• 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 glipizide (Glucotrol), glyburide (Glynase), pioglitazone (Actos), repaglinide (Prandin), and rosiglitazone (Avandia)
• Doxepin (Silenor)
• Eliglustat (Cerdelga)
• Everolimus (Afinitor, Zortress)
• Flibanserin (Addyi)
• HIV medicines such as atazanavir (Reyataz), cobicistat (Tybost), darunavir (Prezista), delavirdine (Rescriptor), dolutegravir (Tivicay), efavirenz (Sustiva), elvitegravir (Vitekta), etravirine (Intelence), fosamprenavir (Lexiva), indinavir (Crixivan), lopinavir/ritonavir (Kaletra), nelfinavir (Viracept), nevirapine (Viramune), rilpivirine (Edurant), ritonavir (Norvir), saquinavir (Invirase), stavudine (Zerit), and tipranavir (Aptivus)
• Hormonal birth control implants, IUDs, patches, pills, shots, and vaginal rings, and hormones such as conjugated estrogens (Premarin), estradiol (Climara, Estrace, Estraderm, Vivelle), and norethindrone (Aygestin, Micronor) (Talk to your healthcare provider if you need birth control.)
• Immunosuppressants such as cyclosporine (Gengraf, Neoral, Sandimmune), sirolimus (Rapamune), and tacrolimus (Astagraf, Prograf, Protopic)
• Malaria medicines such as artemether/lumefantrine (Coartem), chloroquine, and mefloquine
• 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 low sodium levels such as conivaptan (Vaprisol) and tolvaptan (Samsca)
• Medicines to treat or prevent blood clots such as apixaban (Eliquis), cilostazol, dabigatran (Pradaxa), rivaroxaban (Xarelto), ticagrelor (Brilinta), vorapaxar (Zontivity), and warfarin (Coumadin)
• Medicines to treat pulmonary hypertension such as macitentan (Opsumit), sildenafil (Revatio), and tadalafil (Adcirca)
• Mifepristone (Korlym, Mifeprex)
• Muscle relaxants such as baclofen (Gablofen, Lioresal), carisoprodol (Soma), cyclobenzaprine (Amrix), dantrolene (Dantrium), methocarbamol (Robaxin), orphenadrine (Norflex), and tizanidine (Zanaflex)
• Naloxegol (Movantik)
• Narcotic pain medicines such as codeine, fentanyl (Abstral, Actiq, Duragesic, Fentora, Sublimaze), hydrocodone/acetaminophen (Norco, Vicodin), hydromorphone (Dilaudid, Exalgo), meperidine (Demerol), methadone (Dolophine, Methadose), morphine (Kadian, MS Contin), oxycodone (OxyContin, Roxicodone), oxycodone/acetaminophen (Percocet, Roxicet), and pentazocine (Talwin)
• Natural remedies such as gotu kola, kava, St. John's wort, and valerian
• Nausea medicines such as aprepitant (Emend), netupitant/palonosetron (Akynzeo), prochlorperazine (Compro), and promethazine
• Nintedanib (Ofev)
• Orlistat (alli, Xenical)
• Paroxetine (Brisdelle, Paxil, Pexeva)
• Praziquantel (Biltricide)
• Propranolol (Hemangeol, Inderal, InnoPran)
• Ranolazine (Ranexa)
• Riociguat (Adempas)
• Roflumilast (Daliresp)
• Sleeping pills such as flurazepam, suvorexant (Belsomra), temazepam (Restoril), triazolam (Halcion), zaleplon (Sonata), and zolpidem (Ambien, Edluar, Intermezzo)
• Stimulants such as armodafinil (Nuvigil) and modafinil (Provigil)
• Tamoxifen
• Tasimelteon (Hetlioz)
• Theophylline
• Tofacitinib (Xeljanz)
• Tretinoin (Atralin, Renova, Retin-A)

Do not drink alcohol while you are taking this medicine.

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.