• Butalbital/acetaminophen is a combination pain-reliever (analgesic) containing butalbital and acetaminophen.
• Butalbital belongs to the class of medicines called barbiturates. When used for pain due to tension headaches experts believe it works by relaxing muscle contractions and causing sedation via an enhancement of the inhibitory effects of GABA (a neurotransmitter that regulates communication between brain cells).
• Experts aren't sure exactly how acetaminophen works, but suspect it may activate descending serotonergic inhibitory pathways in the CNS and other nociceptive pathways (nociceptive pain describes pain from physical or potential damage to the body such as that from a sports injury or dental procedure). Inhibition of the hypothalamic heat-regulating center gives acetaminophen its fever-lowering effect.
• Butalbital/acetaminophen belongs to the class of medicines known as barbiturates because it contains butalbital. It may also be called a combination analgesic.

• May be used short-term to relieve episodic tension-type headaches.
• Available as capsules and tablets.
• Available in two strengths: butalbital 25mg/acetaminophen 325mg and butalbital 50mg/acetaminophen 300mg to 325mg.
• Generic butalbital/acetaminophen is available.

If you are between the ages of 18 and 60, take no other medication or have no other medical conditions, side effects you are more likely to experience include:

• Dizziness, drowsiness, lightheadedness, sedation, shortness of breath, nausea, vomiting, abdominal pain, or an intoxicated feeling are the most commonly reported side effects.
• Other side effects, such as constipation, excessive sweating, itch, and mental confusion are less common.
• Butalbital is habit-forming and there is a high risk of dependence with extended and repeated use of butalbital/acetaminophen. Therefore it is not considered a first-choice medicine for headaches.
• May cause medication-overuse headache with repeated use (more than 3 days per month) and a withdrawal syndrome (symptoms include worsened headache, nausea/vomiting, restlessness, anxiety, disturbed sleep, and sweating) upon discontinuation. When stopping acetaminophen/butalbital/caffeine that has been taken long-term, taper the dose down and discontinue slowly over 2 to 4 weeks. If a person has developed chronic migraines, consider replacing the acetaminophen/butalbital/caffeine with phenobarbital and gradually tapering down.
• Taken every four hours as needed but do not exceed the maximum dose.
• The potential for liver damage with the acetaminophen component exists, even at recommended dosages. The risk is increased with higher dosages, with chronic alcohol use, with some medications, and in patients with significant liver disease.
• May not be suitable for some people, including the elderly and people with kidney or liver disease.
• Although butalbital/acetaminophen may be prescribed for migraine headaches, it is not FDA approved for this use and evidence does not support its use for migraine.
• May interact with many other medications including those that also cause sedation such as opioids, benzodiazepines, and sedating antihistamines. Alcohol should be avoided.
• Although acetaminophen/butalbital may be prescribed for migraine headaches, it is not FDA approved for this use and evidence does not support its use for migraine.
• Not recommended during pregnancy because butalbital crosses the placenta and withdrawal seizures have been reported in newborns whose mothers took butalbital/acetaminophen. Do not use while breastfeeding.

Note: In general, seniors or children, people with certain medical conditions (such as liver or kidney problems, heart disease, diabetes, seizures) or people who take other medications are more at risk of developing a wider range of side effects. View complete list of side effects

• May be administered without regard to food; although food may decrease any reported stomach upset.
• Do not overuse butalbital/acetaminophen because you may become addicted to it and have difficulty stopping it.
• Over-use of butalbital/acetaminophen can also result in a medication-overuse headache (also known as a rebound headache) which occurs when analgesics are taken too frequently to relieve a headache. Only use butalbital/acetaminophen at the minimum effective dose and for a short period.
• Never share your butalbital/acetaminophen with anybody else.
• If you have been taking butalbital/acetaminophen regularly, or if you think you have become addicted to it, talk to your doctor about slowly withdrawing it, as sudden withdrawal may precipitate a withdrawal syndrome (symptoms include anxiety, dizziness, hallucinations, muscle twitching, nausea, seizures, sleeplessness, or tremor).
• Butalbital/acetaminophen can cause sedation and affect your ability to drive or operate machinery.
• Do not drink more than two alcoholic drinks a day if you are a man or one alcoholic drink per day if you are a woman and taking butalbital/acetaminophen.
• Talk to your doctor or pharmacist before taking any other medications including those bought over-the-counter because they may not be compatible with butalbital/acetaminophen.
• Talk to your doctor if you have any side effects of concern. Seek urgent medical advice if you develop an allergic-type reaction (difficulty breathing or swallowing, rash, or facial swelling) soon after taking butalbital/acetaminophen.
• Not recommended for women who are pregnant or breastfeeding.
• Butalbital/acetaminophen contains acetaminophen which may be "hidden" in other cough/cold medicines. The total dose of acetaminophen from any source should not exceed 4000mg per day (24 hours).

• The pain-relieving effects of acetaminophen are reached within 30-60 minutes of administration.
• Butalbital is well absorbed from the gastrointestinal tract and produces an analgesic effect within one to two hours. Butalbital is metabolized in the liver by the CYP450 enzyme system which means it has the potential to interact with a large number of other drugs. Butalbital has an average half-life of around 35 hours, which means it lasts for a long time in the body and repeated doses may have a cumulative effect, increasing the risk of side effects.

Medicines that interact with butalbital/acetaminophen may either decrease its effect, affect how long it works for, increase side effects, or have less of an effect when taken with butalbital/acetaminophen. An interaction between two medications does not always mean that you must stop taking one of the medications; however, sometimes it does. Speak to your doctor about how drug interactions should be managed.

Common medications that may interact with butalbital/acetaminophen include:

• acetaminophen
• antidepressants, such as tricyclic antidepressants (eg, amitriptyline), monoamine oxidase inhibitors (eg, isocarboxazid, phenelzine, and tranylcypromine), or SSRIs (eg, fluoxetine, sertraline)
• anticonvulsants, such as carbamazepine, divalproex, lamotrigine, phenytoin, phenobarbital, or primidone
• antipsychotics (such as butyrophenones, phenothiazines, or thioxanthenes) and atypical antipsychotics (eg, olanzapine, quetiapine, ziprasidone)
• any medication that may cause drowsiness, such as amphetamines, benzodiazepines (eg, diazepam, lorazepam), first-generation antihistamines (such as doxylamine or promethazine), metoclopramide, or opioids (such as codeine, fentanyl, or morphine)
• atomoxetine
• azelastine
• barbiturates
• beta-blockers such as atenolol or sotalol
• buprenorphine
• cannabis
• cyclosporine
• dextromethorphan
• duloxetine
• heart medications such as diltiazem or verapamil
• HIV medications such as ritonavir
• migraine medications, such as ergotamine or dihydroergotamine
• muscle relaxants, such as cyclobenzaprine
• naltrexone
• other medications that contain acetaminophen or an opioid either in combination or as the sole ingredient
• pentazocine
• prilocaine
• rifampin
• sodium oxybate
• tamsulosin
• tramadol
• warfarin.

Avoid drinking alcohol or taking illegal or recreational drugs while taking acetaminophen/butalbital/caffeine because it may enhance the hepatotoxic effect of acetaminophen.

Note that this list is not all-inclusive and includes only common medications that may interact with butalbital/acetaminophen. You should refer to the prescribing information for butalbital/acetaminophen for a complete list of interactions.