How does this medication work? What will it do for me?

This medication is a combination product that contains acetylsalicylic acid (ASA), butalbital, and caffeine. ASA is used to relieve pain. Butalbital, a barbiturate, is a relaxant. Caffeine helps increase the effectiveness of pain relief.

This medication is used to treat tension (or muscle contraction) headaches.

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

Your doctor may have suggested this medication 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 this medication, speak to your doctor. Do not stop taking this medication without consulting your doctor.

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

What form(s) does this medication come in?

Pronal is no longer being manufactured for sale in Canada. For brands that may still be available, search under ASA – caffeine – butalbital. This article is being kept available for reference purposes only. If you are using this medication, speak with your doctor or pharmacist for information about your treatment options.

How should I use this medication?

The recommended adult dose of ASA–caffeine–butalbital is 2 capsules at once followed by 1 capsule every 3 to 4 hours if necessary. Do not take more than 6 tablets or capsules in one day.

Many things can affect the dose of a 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.

It is very important to use this medication exactly as prescribed by your doctor. If you miss a dose, take it as soon as possible and continue with your regular schedule. If it is almost time for your next dose, skip the missed dose and continue with your regular dosing schedule. Do not take a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.

This medication has the potential for becoming habit-forming if taken for long periods of time. It should be avoided in situations where pain medication is required on a daily basis. If you have been taking this medication regularly and the medication is stopped suddenly, you may experience withdrawal symptoms such as anxiety, sweating, trouble sleeping, shakiness, nausea, tremors, diarrhea, or hallucinations. It may be necessary to reduce the dose gradually to reduce the severity of withdrawal effects. Speak to your doctor for guidance on stopping this medication.

Store this medication at room temperature, protect it from light and moisture, 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.

Who should NOT take this medication?

Do not take this medication if you:

  • are allergic to ASA, caffeine, butalbital, or any ingredients of the medication
  • are overdosed on or intoxicated by alcohol, hypnotics, analgesics, or psychotropic medications
  • have a history of blood clotting problems
  • have had nasal polyps (growth in the nose), angioedema (swelling under the skin), or difficulty breathing as a result of taking ASA or other nonsteroidal anti-inflammatory drugs (NSAIDs)
  • have porphyria (a condition of the liver)
  • have stomach ulcers or duodenal ulcers

What side effects are possible with this medication?

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 this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. 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.

  • constipation
  • decreased concentration or memory
  • dizziness or lightheadedness
  • drowsiness
  • heartburn or indigestion
  • nausea, vomiting, or stomach pain

Although most of these 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:

  • decreased coordination
  • fast, irregular, or pounding heartbeat
  • increased frequency of infections
  • irritability
  • mood swings
  • signs of anemia (low red blood cells; e.g., dizziness, pale skin, unusual tiredness or weakness, shortness of breath)
  • signs of bleeding (e.g., bloody nose, blood in urine, coughing blood, bleeding gums, cuts that don't stop bleeding)
  • 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)
  • skin rash
  • symptoms of overdose such as cold, clammy skin, abnormally slow or weak breathing, severe dizziness, confusion, slow heartbeat, or extreme uncontrollable flapping movements of the hands (especially in elderly patients)
  • symptoms of a stomach ulcer (e.g., heart burn, long lasting stomach pain, decreased appetite, weight loss)
  • tremor
  • unusual excitement (mild)

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

  • signs of bleeding in the stomach (e.g., bloody, black, or tarry stools; spitting up of blood; vomiting blood or material that looks like coffee grounds)
  • signs of a serious allergic reaction (e.g., difficulty breathing; coughing; shortness of breath; tightness in chest; skin rash; itching; hives; swelling of the eyelids, face, lips, or tongue)
  • signs of Reye's syndrome (e.g., rash on the palms of hands and feet, high fever, weakness, confusion, severe vomiting)
  • 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

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 this medication.

Are there any other precautions or warnings for this medication?

Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.


June 8, 2021

Health Canada has issued new information concerning the use of non-steroidal anti-inflammatory drugs (NSAIDs). To read the full Health Canada Advisory, visit Health Canada's web site at

Abdominal conditions: This medication may make the diagnosis of abdominal conditions more difficult or it may worsen these conditions. If you have any abdominal conditions such as stomach ulcers, inflammatory or obstructive bowel disease, acute cholecystitis, or pancreatitis, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Bleeding: This medication contains ASA (acetylsalicylic acid), which can increase the risk of bleeding or may prolong bleeding time after an injury. If you have blood-clotting problems, a history of bleeding tendencies or stomach ulcers, or are taking blood-thinning medication, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Dependence: Long-term use of butalbital may be habit-forming and lead to physical dependence on the medication. This medication has the potential for being abused and should be avoided in treating chronic pain conditions that may lead to continuous daily use. If you have a history of past or current substance use problems, you may be at greater risk of developing abuse or addiction while taking this medication.

Drowsiness/reduced alertness: This medication may cause drowsiness. Do not drive, operate machinery, or perform other potentially hazardous tasks until you have determined how this medication affects you.

Head injury: People with head injuries or increased pressure in the head may have a higher risk of experiencing side effects (breathing problems) or worsening of their condition while taking this medication. These people should discuss with their doctor how this medication may affect their medical condition, how their medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Kidney function: Kidney disease or reduced kidney function may cause butalbital to build up in the body, causing side effects. Taking ASA for a long period of time may increase the risk of developing kidney disease. If you have kidney disease or reduced kidney function, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Liver function: If you have liver disease or decreased liver function, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Medical conditions: If you have any of the following conditions, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed:

  • Addison's disease
  • enlarged prostate (benign prostatic hypertrophy)
  • hypothyroidism
  • narrowing of the urethra
  • osteomalacia
  • osteoporosis

Medication overuse headache: ASA–caffeine–butalbital may contribute to medication overuse headache (rebound headaches). Daily use of this medication is not recommended.

Reye's syndrome: ASA may be linked to Reye's syndrome (a rare disease affecting the brain and liver). It should be used with caution by children, teenagers, and young adults with influenza or chickenpox. Report any symptoms of Reye's syndrome, such as high fever, weakness, fast breathing, unresponsiveness and rash on the palms to a doctor as soon as possible.

Pregnancy: This medication should not be taken during the last 3 months of pregnancy, as ASA may cause longer labour and delivery or cause bleeding in either the baby or birth parent. ASA, like other NSAIDs, can also cause kidney damage in the developing baby if it is taken during pregnancy. Ibuprofen should be avoided after 20 weeks of pregnancy and must not be taken in the last 3 months of pregnancy.

It is not known if ASA–caffeine–butalbital causes harm to the developing baby. During the first 6 months of pregnancy, this medication should not be used unless the benefits outweigh the risks. If you become pregnant while taking this medication, contact your doctor immediately.

Breast-feeding: This medication passes into breast milk. If you are breast-feeding and are taking ASA–caffeine–butalbital, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.

Children: The safety and effectiveness of using this medication have not been established for children. ASA–caffeine–butalbital is not recommended for people less than 18 years of age.

Seniors: People over the age of 65 are at an increased risk of experiencing side effects of this medication. A lower dose may be needed.

What other drugs could interact with this medication?

There may be an interaction between ASA–caffeine–butalbital and any of the following:

  • acetazolamide
  • alcohol
  • aldesleukin
  • alendronate
  • alpha agonists (e.g., clonidine, guanfacine, methyldopa)
  • alpha-blockers (e.g., doxazosin, prazosin, tamsulosin, terazosin)
  • amphetamines (e.g., dextroamphetamine, lisdexamfetamine)
  • anagrelide
  • angiotensin receptor blockers (ARBs; e.g., candesartan, irbesartan, losartan)
  • angiotensin converting enzyme inhibitors (ACEIs; e.g., captopril, ramipril)
  • antihistamines (e.g., chlorpheniramine, diphenhydramine, doxylamine)
  • antipsychotic medications (e.g., chlorpromazine, haloperidol, quetiapine, risperidone)
  • apixaban
  • atomoxetine
  • azelastine
  • other barbiturates (e.g., butalbital, phenobarbital)
  • benzodiazepines (e.g., alprazolam, diazepam, lorazepam)
  • beta-blockers (e.g., atenolol, propranolol)
  • birth control pills
  • brimonidine
  • fast-acting bronchodilators (e.g., salbutamol, terbutaline)
  • long-acting bronchodilators (e.g., formoterol, indacaterol, salmeterol)
  • buprenorphine
  • calcium channel blockers (e.g., amlodipine, diltiazem, nifedipine, verapamil)
  • cannabis
  • celecoxib
  • chloral hydrate
  • clopidogrel
  • corticosteroids (e.g., prednisone)
  • dabigatran
  • decongestant cold medications (e.g., phenylephrine, pseudoephedrine)
  • decongestant eye drops and nose sprays (e.g., naphazoline, oxymetazoline, xylometazoline)
  • deferasirox
  • diabetes medications (e.g., acarbose, canagliflozin, glyburide, insulin, metformin, rosiglitazone)
  • diphenoxylate
  • disopyramide
  • diuretics (water pills; e.g., furosemide, hydrochlorothiazide, spironolactone)
  • edoxaban
  • efavirenz
  • entacapone
  • epinephrine
  • flibanserin
  • flunarizine
  • general anesthetics (medications used to put people to sleep before surgery)
  • garlic
  • ginger
  • ginkgo biloba
  • ginseng
  • heparin
  • hydralazine
  • icosapent ethyl
  • leflunomide
  • lemborexant
  • levodopa
  • levonorgestrel
  • levothyroxine
  • linezolid
  • lithium
  • low molecular weight heparins (e.g., dalteparin, enoxaparin, tinzaparin)
  • methadone
  • methotrexate
  • methylphenidate
  • metoclopramide
  • mexiletine
  • mifepristone
  • mirtazapine
  • modafinil
  • monoamine oxidase inhibitors (MAOIs e.g., phenelzine, rasagiline, selegiline, tranylcypromine)
  • multivitamins and minerals
  • muscle relaxants (e.g., baclofen, cyclobenzaprine, methocarbamol, orphenadrine, tizanidine)
  • nabilone
  • narcotic pain relievers (e.g., codeine, fentanyl, morphine)
  • nitrates (e.g., nitroglycerin, isosorbide dinitrate, isosorbide mononitrate)
  • nonsteroidal anti-inflammatory drugs (e.g., ibuprofen, ketorolac, naproxen)
  • obinutuzumab
  • omega-3 fatty acids
  • ozanimod
  • pentoxifylline
  • perampanel
  • pizotifen
  • pomalidomide
  • pramipexole
  • prasugrel
  • pregabalin
  • protein kinase inhibitors (e.g., dasatinib, ibrutinib, sunitinib)
  • quinolone antibiotics (e.g., ciprofloxacin, norfloxacin, moxifloxacin)
  • riociguat
  • rivaroxaban
  • ropinirole
  • rotigotine
  • scopolamine
  • selective serotonin reuptake inhibitors (SSRIs; e.g., citalopram, fluoxetine, sertraline)
  • seizure medications (e.g., clobazam, levetiracetam, phenytoin, primidone, topiramate, valproic acid)
  • serotonin/norepinephrine reuptake inhibitors (e.g., desvenlafaxine, duloxetine, venlafaxine)
  • sodium oxybate
  • somatostatin analogues (e.g., lanreotide, octreotide, pasireotide)
  • sulfadiazine
  • sulfamethoxazole
  • teriflunomide
  • tetrabenazine
  • tetracyclines (e.g., doxycycline, minocycline, tetracycline)
  • thalidomide
  • theophyllines (e.g., aminophylline, theophylline)
  • ticagrelor
  • tipranavir
  • trazodone
  • tretinoin
  • tricyclic antidepressants (e.g., amitriptyline, desipramine, nortriptyline)
  • vaccines
  • warfarin
  • 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 this medication. 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.

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