Phenobarb (Phenobarbital) belongs to the class of medications called barbiturates. It is used to treat Insomnia (difficulty sleeping) and as a sedative to relieve the symptoms of anxiety or tension. It is also used for the control of certain types of seizures. It works by slowing down the brain and nervous system.

Phenobarb (Phenobarbital) is also used to reduce bilirubin levels in newborn babies. Bilirubin is a substance produced by the body and removed by the liver. Sometimes a newborn baby's liver needs some time to start to work effectively.

Phenobarb (Phenobarbital) may be available under multiple brand names and/or in several different forms. Any specific brand name of Phenobarb (Phenobarbital) may not be available in all of the forms or approved for all of the conditions discussed here. As well, some forms of Phenobarb (Phenobarbital) may not be used for all of the conditions discussed here.

Your doctor may have suggested Phenobarb (Phenobarbital) for conditions other than those listed in these drug information articles. If you have not discussed this with your doctor or are not sure why you are taking Phenobarb (Phenobarbital), speak to your doctor. Do not stop taking Phenobarb (Phenobarbital) without consulting your doctor.

Do not give Phenobarb (Phenobarbital) to anyone else, even if they have the same symptoms as you do. It can be harmful for people to take Phenobarb (Phenobarbital) if their doctor has not prescribed it.

Adults (seizure prevention): The recommended adult dose of Phenobarb (Phenobarbital) to prevent seizures ranges from 50 mg to 100 mg taken twice or three times daily. The maximum dose is 600 mg daily.

Children (seizure prevention): The recommended children's dose ranges from 15 mg to 50 mg taken twice or three times daily.

Adults (treatment of insomnia/sedative): The recommended adult dose of Phenobarb (Phenobarbital) for insomnia ranges from 100 mg to 200 mg taken at bedtime. The recommended adult dose as a sedative ranges from 30 mg to 90 mg daily in 2 or 3 divided doses.

Children (sedative): The recommended sedative dose for children is 2 mg per kilogram of body weight, taken 3 times daily.

Use an oral syringe to measure each dose of the liquid, as it gives a more accurate measurement than household teaspoons.

Many things can affect the dose of medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are taking the medication without consulting your doctor.

Phenobarb (Phenobarbital) may be habit-forming if taken for long periods of time. You may experience withdrawal effects if you stop taking Phenobarb (Phenobarbital) suddenly after extended use. If you plan on stopping the medication, your doctor may want you to reduce the dose gradually to reduce the severity of withdrawal effects.

It is important that Phenobarb (Phenobarbital) be taken exactly as prescribed by your doctor. If you have been taking Phenobarb (Phenobarbital) on a regular basis, do not stop taking Phenobarb (Phenobarbital) without talking to your doctor first, and do not increase the dose of Phenobarb (Phenobarbital) without first talking with your doctor.

If you miss a scheduled dose, take it as soon as possible and continue on with your regular schedule. If it is almost time for your next dose, skip the missed dose and continue on with your regular dosing schedule. Do not take a double dose of Phenobarb (Phenobarbital). If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.

Store Phenobarb (Phenobarbital) at room temperature and keep it out of the reach of children.

Do not dispose of medications in wastewater (e.g. down the sink or in the toilet) or in household garbage. Ask your pharmacist how to dispose of medications that are no longer needed or have expired.

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.

The side effects listed below are not experienced by everyone who takes Phenobarb (Phenobarbital). If you are concerned about side effects, discuss the risks and benefits of Phenobarb (Phenobarbital) with your doctor.

The following side effects have been reported by at least 1% of people taking Phenobarb (Phenobarbital). Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

• clumsiness or unsteadiness
• Constipation
• Diarrhea
• dizziness
• drowsiness
• fatigue
• feeling faint or lightheaded
• "hangover" effect
• headache
• Low Blood Pressure
• nausea
• nightmares or trouble sleeping
• spinning sensation
• trouble concentrating
• vomiting

Although most of the side effects listed below don't happen very often, they could lead to serious problems if you do not seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

• abdominal pain
• bone pain or fractures
• confusion
• hyperactivity in children
• signs of Anemia (low red blood cells; e.g., dizziness, pale skin, unusual tiredness or weakness, shortness of breath)
• signs of clotting problems (e.g., unusual nosebleeds, bruising, blood in urine, coughing blood, bleeding gums, cuts that don't stop bleeding)
• signs of depression (e.g., poor concentration, changes in weight, changes in sleep, decreased interest in activities, thoughts of suicide)
• signs of infection (symptoms may include Fever or chills, severe diarrhea, shortness of breath, prolonged dizziness, headache, stiff neck, weight loss, or listlessness)
• signs of liver problems (e.g., nausea, vomiting, diarrhea, loss of appetite, weight loss, yellowing of the skin or whites of the eyes, dark urine, pale stools)
• symptoms of low sodium levels in the blood (e.g., achy, stiff or uncoordinated muscles, confusion, tiredness, weakness)
• unusual excitement
• vision changes (e.g., blurred vision, double vision)

Stop taking the medication and seek immediate medical attention if any of the following occur:

• signs of a severe skin reaction such as blistering, peeling, a rash covering a large area of the body, a rash that spreads quickly, or a rash combined with fever or discomfort
• signs of a serious allergic reaction (e.g., abdominal cramps, difficulty breathing, nausea and vomiting, or swelling of the face and throat)
• thought of suicide or self-harm
• weak or shallow breathing

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking Phenobarb (Phenobarbital).

Elixir

Each mL of clear red liquid contains 5 mg of Phenobarb (Phenobarbital) USP. Nonmedicinal ingredients: alcohol, anise oil, FD&C Red No. 2, glycerin, methyl paraben, natural and artificial flavour (lemon and orange), propyl paraben, purified water, sodium chloride, sodium cyclamate, and sucrose.

Tablets

15 mg
Each white, round, biconvex tablet, debossed with 'PH' on one side and '15' on the other side contains 15 mg of Phenobarb (Phenobarbital). Nonmedicinal ingredients: gelatin, lactose monohydrate, maize starch, microcrystalline cellulose and stearic acid..

30 mg
Each white, round, biconvex tablet, debossed with 'PH' on one side and '30' on the other side contains 30 mg of Phenobarb (Phenobarbital). Nonmedicinal ingredients: gelatin, lactose monohydrate, maize starch, microcrystalline cellulose and stearic acid..

60 mg
Each white, round, biconvex tablet, debossed with 'PH' on one side and '60' on the other side contains 60 mg of Phenobarb (Phenobarbital). Nonmedicinal ingredients: gelatin, lactose monohydrate, maize starch, microcrystalline cellulose, silicon dioxide and stearic acid.

100 mg
Each white, round, biconvex tablet, debossed with 'PH' on one side and '100' on the other side contains 100 mg of Phenobarb (Phenobarbital). Nonmedicinal ingredients: gelatin, lactose monohydrate, maize starch, microcrystalline cellulose, silicon dioxide and stearic acid.

Do not use Phenobarb (Phenobarbital) if you:

• are allergic to Phenobarb (Phenobarbital) or any ingredients of Phenobarb (Phenobarbital)
• have Alcoholism
• have drug dependence
• have kidney impairment
• have liver impairment
• have porphyria
• have reduced lung function
• have severe respiratory Depression
• have Sleep Apnea
• have suicidal tendencies
• have uncontrolled pain

There may be an interaction between Phenobarb (Phenobarbital) and any of the following:

• Abiraterone
• Acetaminophen
• albendazole
• alcohol
• Aliskiren
• alpha agonists (e.g., Clonidine, methyldopa)
• alpha blockers (e.g., Alfuzosin, Doxazosin, Silodosin, Tamsulosin)
• Amiodarone
• amphetamines (e.g., Dextroamphetamine, Lisdexamfetamine)
• angiotensin converting enzyme inhibitors (ACEIs; Captopril, Ramipril)
• angiotensin receptor blockers (ARBs; e.g., Candesartan, Irbesartan, Losartan)
• anti-cancer medications (e.g., Cabazitaxel, Docetaxel; Doxorubicin; Etoposide, Ifosfamide, Irinotecan, Vincristine)
• antihistamines (e.g., cetirizine, doxylamine, Diphenhydramine, Hydroxyzine, Loratadine)
• antipsychotics (e.g., Chlorpromazine, Clozapine, Haloperidol, Olanzapine, Quetiapine, Risperidone)
• Apixaban
• Aprepitant
• azelastine
• "azole" antifungals (e.g., itraconazole, ketoconazole, Voriconazole)
• barbiturates (e.g., butalbital, pentobarbital Phenobarb (Phenobarbital))
• benzodiazepines (e.g., Chlordiazepoxide, Clonazepam, Diazepam, Lorazepam)
• beta-adrenergic blockers (e.g., Atenolol, betaxolol, Carvedilol, Propranolol, Sotalol)
• birth control pills
• brimonidine
• Buprenorphine
• Bupropion
• Buspirone
• Calcitriol
• calcium channel blockers (e.g., Amlodipine, Diltiazem, Nifedipine, Verapamil)
• Canagliflozin
• cannabis
• Celecoxib
• chloral hydrate
• chloroquine
• Cholestyramine
• clindamycin
• Clopidogrel
• Cobicistat
• conivaptan
• oral corticosteroids (e.g., Dexamethasone, Hydrocortisone, Prednisone)
• cyclosporinedabrafenib
• Dantrolene
• Dapsone
• Darifenacin
• Deferasirox
• Diclofenac
• Disopyramide
• Dronedarone
• Enzalutamide
• estrogens (e.g., conjugated estrogen, Estradiol, ethinyl estradiol)
• Everolimus
• Exemestane
• Fesoterodine
• Flutamide
• folic acid
• "gliptin" Diabetes medications (e.g., Linagliptin, Saxagliptin, Sitagliptin)
• Guanfacine
• Hepatitis C antivirals (e.g., daclatasvir, dasabuvir, ledipasvir, paritaprevir, ombitasvir, sofosbuvir)
• HIV non-nucleoside reverse transcriptase inhibitors (NNRTIs; e.g., delavirdine, efavirenz, etravirine, nevirapine)
• HIV protease inhibitors (e.g., atazanavir, indinavir, ritonavir, saquinavir)
• HIV nucleoside reverse transcriptase inhibitors (NRTIs; e.g., abacavir, didanosine, lamivudine, tenofovir, zidovudine)
• HIV integrase inhibitors (e.g., dolutegravir, elvitegravir)
• isoniazid
• Ivabradine
• lidocaine
• Macitentan
• macrolide antibiotics (e.g., clarithromycin, erythromycin)
• magnesium sulfate
• maraviroc
• Mefloquine
• melatonin
• Methadone
• Methylphenidate
• Metronidazole
• Mexiletine
• mifepristone
• Mirtazapine
• multivitamins
• muscle relaxants (e.g., Baclofen, Cyclobenzaprine, methocarbamol, orphenadrine)
• Modafinil
• Montelukast
• Naloxegol
• narcotic pain relievers (e.g., Codeine, Fentanyl, Morphine, Oxycodone)
• nefazodone
• nitrates (e.g., isosorbide dinitrate, isosorbide mononitrate)
• Olopatadine
• Ondansetron
• Orlistat
• Pioglitazone
• Pramipexole
• praziquantel
• Primaquine
• progestins (e.g., Dienogest, Levonorgestrel, medroxyprogesterone, Norethindrone)
• Prasugrel
• protein kinase inhibitors (e.g., Bosutinib, Dasatinib, imatinib, Nilotinib)
• proton pump inhibitors (e.g., Lansoprazole, Omeprazole)
• pyridoxine
• quinidine
• quinine
• Rasagiline
• Repaglinide
• rifabutin
• rifampin
• rilpivirine
• Riluzole
• Rivaroxaban
• Roflumilast
• Romidepsin
• Ropinirole
• Rosiglitazone
• seizure medications (e.g., Carbamazepine, Clobazam, Levetiracetam, Phenobarb (Phenobarbital), Phenytoin, primidone, Topiramate, Valproic acid, zonisamide)
• selective serotonin reuptake inhibitors (SSRIs; e.g., Citalopram, Fluoxetine, Paroxetine, Sertraline)
• Selegiline
• Sildenafil
• Sirolimus
• Solifenacin
• somatostatin
• "statin" anti-cholesterol medications (e.g., Atorvastatin, Lovastatin, Simvastatin)
• sulfonamide antibiotics (e.g., sulfadiazine, sulfamethoxazole, sulfisoxazole)
• sulfonamide diabetes medications (e.g., Gliclazide, Glimepiride, Glyburide)
• Tacrolimus
• Tadalafil
• Tamoxifen
• Tapentadol
• tetracyclines (e.g., doxycycline, Minocycline, Tetracycline)
• theophyllines (e.g., Aminophylline, Oxtriphylline, Theophylline)
• thiazide diuretics (e.g., chlorothiazide, Hydrochlorothiazide)
• Ticagrelor
• Ticlopidine
• Tofacitinib
• tolcapone
• Tolterodine
• Tolvaptan
• Tramadol
• Tranylcypromine
• Trazodone
• tretinoin
• tricyclic antidepressants (e.g., Amitriptyline, Clomipramine, Desipramine, Trimipramine)
• Trimethoprim
• Ulipristal
• Venlafaxine
• Warfarin
• Zafirlukast
• Zolpidem
• Zopiclone

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

• stop taking one of the medications,
• change one of the medications to another,
• change how you are taking one or both of the medications, or
• leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with Phenobarb (Phenobarbital). Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the Nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.