M523 (Acetaminophen and Oxycodone 325 mg / 10 mg)

This pill is white, capsule-shaped and with imprint “M523.” Manufactured by Mallinckrodt Pharmaceuticals, it is used to treat moderate to moderately severe pain.

Acetaminophen and Oxycodone is a combination of two pain relievers and belongs to the drug class narcotic analgesic combinations. It consists of an opioid or narcotic pain reliever oxycodone, and a non-opioid pain reliever, acetaminophen. Both work in the brain and nervous system to decrease pain.

This medicine is available  in tablet and oral solution forms, extended-release forms, as well as some cost-saving generic versions.

Side Effects

Tell the doctor if symptoms of nausea, vomiting, constipation, lightheadedness, dizziness, or drowsiness persist. Some symptoms may not be experienced by other people and some side effects disappear with over time use.

Get medical help right away if you experience rash; hives; breathing problems; swelling of the mouth face, lips, throat, or tongue; urinary problems; heartbeat irregularities; confusion; hallucinations; mental or mood changes; seizures/convulsions; unusual bleeding, bruising, tiredness, and weakness, etc.

Remember that your doctor has prescribed this medication because he or she has judged that the benefit to you is greater than the risk of side effects. This is not a complete list of side effects. Report to your doctor symptoms not listed above or if these side effects are continuous, unusual and bothersome. Discuss with your doctor the advantages and disadvantages of taking this medication and how to lessen its side effects.

Acetaminophen and Oxycodone Tips and Warnings

Don’t take this medicine beyond the amount prescribed by your doctor. Excessive acetaminophen is dangerous and can cause liver damage.

Opioids like oxycodone can cause constipation. Do not take stool softeners or laxatives without telling your doctor first.

Do not take this medicine if you have allergies to acetaminophen/hydrocodone. Inform your doctor if you have allergies to some other medicines, food, and other substances.

Do not use this pill if you are pregnant, planning to get pregnant, or breastfeeding.

Tell the doctor the following before taking this medicine:

  • If you are taking any prescription/nonprescription drugs, herbal products, vitamins, supplements, etc.
  • If you have history of substance or alcohol abuse from the past.
  • Medical history including past and present conditions

Do not suddenly stop taking this medication as it may cause unpleasant withdrawal symptoms.

Take with food if you feel nauseated or if you are having stomach upset taking this medicine.

Sedation as a side effect can impair reaction skills and affect a person’s ability to drive or operate machinery.

Avoid use of alcohol and medicines that may interact with acetaminophen/hydrocodone such as anticholinergic, cimetidine, azole antifungals, anticoagulants, loop diuretics, etc. Consult with your doctor which medicines are not safe to use while under treatment.

If you miss a dose of acetaminophen/oxycodone and you are taking it regularly, take it as soon as possible. If it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not take 2 doses at once.

Use a measuring device for liquid form of this medication. Swallow whole extended-release form tablets.

The dosage is based on your medical condition and response to treatment. Inform your doctor if you feel like the medicine is not working or if pain doesn’t go away and if you feel you are addicted to this drug.

Use this medicine at the first sign of pain to maximize its effects.

Older adults may be more sensitive to the side effects of this drug, especially confusion, dizziness, drowsiness, and slow/shallow breathing.

To reduce the risk of dizziness and lightheadedness, get up slowly when rising from a sitting or lying position.

Use with caution among children. Safety and effectiveness of this medicine have not yet been confirmed.

Seek emergency help with symptoms of overdose such as slow/shallow breathing, slow heartbeat, coma, nausea, vomiting, loss of appetite, sweating, stomach/abdominal pain, extreme tiredness, yellowing eyes/skin, dark urine.


Store at room temperature away from light and moisture.

Keep all medications away from children and pets.

Properly discard this product when it is expired or no longer needed.


This material is provided for educational purposes only and is not intended for medical advice, diagnosis or treatment.





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