Finding an unfamiliar tablet marked M523 can be worrying. You may want to know whether it is oxycodone, whether it is the same as Percocet, what 10/325 means, or whether the tablet is safe to take. The U.S. prescription product listed by DailyMed with the imprint M523 / 10/325 contains 10 mg of oxycodone hydrochloride and 325 mg of acetaminophen. It is white to off-white, oval or caplet-shaped, about 16 mm long, and has no score line. [1]
However, identifying what a labeled medicine should look like is not the same as proving that an unknown pill is genuine. Counterfeit medicines can look authentic while containing the wrong ingredient, too much or too little medicine, no active ingredient, or other harmful substances. Therefore, the full imprint, appearance, pharmacy label, and source of the medicine all matter. [2]
M523 Pill at a Glance
| Feature | M523 10/325 |
|---|---|
| Imprint | M523 / 10/325 |
| Oxycodone HCl | 10 mg |
| Acetaminophen | 325 mg |
| Color | White to off-white |
| Shape | Oval / caplet-shaped |
| Size | About 16 mm |
| Score | No score |
| Route | Oral |
| DEA schedule | CII |
| NDC family | 0406-0523 |
| Labeler | SpecGx LLC |
The M523 / 10/325 product is labeled by SpecGx LLC and is classified as a Schedule II controlled substance in the United States. [1]
What Is M523 10/325?
M523 is the identifying imprint used on a specific oxycodone-acetaminophen tablet. The 10/325 marking describes its strength: 10 mg of oxycodone hydrochloride and 325 mg of acetaminophen. [1]
Oxycodone is a semi-synthetic opioid analgesic used for pain relief, while acetaminophen is a non-opioid pain reliever and fever reducer. Because this medicine contains oxycodone, it carries important risks including respiratory depression, misuse, physical dependence, addiction, overdose, and death. [1]
How to Identify the M523 Tablet
The labeled M523 product has M523 on one side and 10/325 on the other. It is white to off-white, oval or caplet-shaped, approximately 16 mm long, and not scored. [1]
The no-score detail matters because some online descriptions incorrectly suggest that the tablet has a line for splitting. The M523 / 10/325 tablet is not scored. These physical details can help identify the labeled product, but they cannot confirm what is actually inside an unknown tablet. [1]
Can You Tell If an M523 Pill Is Genuine?
Not reliably by appearance alone.
Counterfeit medicines can closely resemble legitimate prescription drugs and may contain incorrect amounts of medicine, no active ingredient, or other harmful ingredients. [2]
Counterfeit pills sold as prescription opioids may also contain fentanyl, creating a serious overdose risk. [5] Readers who want additional background can also see this site’s article on fentanyl and its risks.
The key distinction is simple: identification is not authentication.
What Is M523 Used For?
Oxycodone-acetaminophen tablets are indicated for the management of pain severe enough to require an opioid analgesic when alternative treatments are inadequate. This opioid combination is generally reserved for situations in which other pain-treatment options are ineffective, not tolerated, or otherwise inadequate. [1]
Because oxycodone carries risks of misuse, addiction, respiratory depression, and overdose, take this medicine only in the dose and manner prescribed for you, and do not share it with anyone else. [1]
Is M523 the Same as Percocet?
Not exactly.
M523 is an imprint identifying a particular generic oxycodone/acetaminophen 10 mg/325 mg tablet. Percocet is a brand-name oxycodone/acetaminophen product.
Although M523 and Percocet 10/325 can contain the same active ingredients and strength, they are different tablet products with different imprints and appearances. [3]
M523 vs M 523, M522, and 512
Small differences in an imprint can identify a different strength or even a completely different medicine.
| Imprint | Identification | Strength |
|---|---|---|
| 512 | Oxycodone + acetaminophen | 5 mg / 325 mg |
| M522 / 7.5/325 | Oxycodone + acetaminophen | 7.5 mg / 325 mg |
| M523 / 10/325 | Oxycodone + acetaminophen | 10 mg / 325 mg |
| M 523 | Bisoprolol fumarate | 5 mg |
The 512, M522, and M523 imprints identify different oxycodone-acetaminophen strengths: 5/325 mg, 7.5/325 mg, and 10/325 mg, respectively. [1] A separate round tablet marked M 523 is identified as bisoprolol fumarate 5 mg. [6]
This is why a pill should not be identified from “523” alone.
Common Side Effects
Common side effects of oxycodone-acetaminophen can include lightheadedness, dizziness, drowsiness or sedation, nausea, vomiting, constipation, and itching. [1]
Because oxycodone can affect alertness and coordination, patients should understand how the medicine affects them before driving or operating dangerous machinery. [1]
Serious Risks and Warnings
Important risks include life-threatening respiratory depression, overdose, addiction, misuse, severe sedation, low blood pressure, and acetaminophen-related liver injury. Serious or fatal respiratory depression can occur with oxycodone, particularly when treatment begins or after a dosage increase. [1]
Opioids can also cause opioid-induced hyperalgesia (OIH), in which pain or sensitivity to pain increases rather than improves. If pain becomes worse after an opioid dose increase, the patient should contact a healthcare professional rather than increasing the dose independently. [1]
Who Should Not Take It?
This medication is contraindicated in several situations, including:
- significant respiratory depression
- acute or severe bronchial asthma in an unmonitored setting or without resuscitation equipment
- known or suspected gastrointestinal obstruction, including paralytic ileus
- hypersensitivity to oxycodone, acetaminophen, or another ingredient in the product
This is not a complete substitute for an individual medical assessment. A qualified prescriber should review a person’s medical conditions and other medicines before treatment.
Drug and Alcohol Interactions
Oxycodone can become much more dangerous when combined with substances that also depress the central nervous system. These include:
- alcohol
- benzodiazepines
- other opioids
- gabapentinoids such as gabapentin or pregabalin
- sedative-hypnotics
- muscle relaxants
- antipsychotics
- other CNS depressants
Combined use can increase the risk of profound sedation, respiratory depression, coma, and death. [1]
Patients should tell their healthcare provider about prescription medicines, over-the-counter drugs, supplements, alcohol, and other substances they use.
Antidepressants and Serotonin Syndrome
Some antidepressants and other medicines affect serotonin. Using opioids with serotonergic drugs can cause serotonin syndrome, a potentially life-threatening reaction.
Relevant medicines can include:
- SSRIs
- SNRIs
- tricyclic antidepressants
- triptans
- mirtazapine
- trazodone
- tramadol
- certain other serotonergic drugs
Oxycodone-acetaminophen is not recommended for patients taking an MAO inhibitor or within 14 days after stopping one.[1]
Possible symptoms can include:
- agitation
- confusion
- sweating
- fever
- fast heartbeat
- abnormal muscle activity
Medical attention is needed if serotonin syndrome is suspected.
Dependence, Addiction, Misuse, and Withdrawal
Physical dependence is a physiological adaptation that can develop with repeated opioid use. If the medicine is abruptly stopped or sharply reduced after dependence develops, withdrawal symptoms can occur. [1]
Addiction is different. It can involve strong urges to use a drug, difficulty controlling use, and continued use despite harmful consequences. Opioid addiction can occur even when a medicine was originally prescribed appropriately. [1]
Misuse can include:
- taking more medicine than prescribed
- taking it more often than directed
- using another person’s prescription
- using oxycodone for non-medical effects
Withdrawal may include:
- restlessness
- sweating
- chills
- muscle aches
- stomach cramps
- nausea
- vomiting
- diarrhea
- anxiety
- trouble sleeping
Opioids should not be abruptly stopped in someone who has become physically dependent; tapering should be individualized. [1]
Acetaminophen and Liver Safety
The 325 mg of acetaminophen in M523 also requires care.
Most reported cases of acetaminophen-related liver injury are associated with doses above 4,000 mg per day, often when more than one acetaminophen-containing product is used. [1]
Important: That does not mean 4,000 mg is a safe personal target for everyone. Liver disease, alcohol use, other medicines, and individual health factors can affect risk.
Patients should check medicine labels for acetaminophen or APAP and avoid accidentally combining multiple acetaminophen-containing products. [1]
Overdose and Naloxone
A suspected opioid overdose is a medical emergency.
Warning signs can include:
- very slow or shallow breathing
- severe sleepiness
- inability to wake
- limpness
- unconsciousness
Emergency medical help should be requested immediately. In the United States, call 911. [4]
Naloxone can rapidly reverse the dangerous effects of an opioid overdose, including opioid-related breathing problems. However, naloxone is a temporary treatment, and overdose symptoms can return. Emergency medical help is still needed after naloxone is given, even if the person appears to improve. In the United States, call 911 and stay with the person until help arrives. [4]
What Should You Do With an Unknown M523 Tablet?
If you find a tablet that appears to match M523 / 10/325 but do not know where it came from, do not take it or give it to someone else.
You can compare the complete imprint and appearance with official product information, but appearance should not be treated as proof of authenticity. If the tablet is supposed to be part of your own prescription but looks different from what you normally receive, compare it with the pharmacy label and ask a licensed pharmacist before taking it. [2]
If someone has already taken an unknown tablet and becomes very sleepy, cannot be awakened, or develops slow or difficult breathing, seek emergency medical help immediately and use naloxone according to its instructions if an opioid overdose is suspected and naloxone is available. [4]
Storage and Disposal
Store oxycodone-acetaminophen securely, out of sight and reach of children, and where other people cannot easily access it. Unused or expired opioid medicine should be disposed of promptly, with a drug take-back option preferred when one is readily available. [1]
Pregnancy and Breastfeeding
Extended opioid use during pregnancy can cause neonatal opioid withdrawal syndrome, which may become life-threatening if it is not recognized and treated. Pregnant patients or those planning pregnancy should discuss opioid treatment with their healthcare provider. [1]
Both oxycodone and acetaminophen can be present in breast milk after maternal use. Oxycodone can be present in breast milk, while acetaminophen may also pass into breast milk in low concentrations.
Breastfed infants exposed to oxycodone should be monitored for:
- excess sleepiness
- breathing problems
- limpness
FAQs
Can M523 Get You High?
Oxycodone can produce euphoria because of its opioid effects. Using prescription oxycodone to become intoxicated is misuse and increases the risk of respiratory depression, addiction, overdose, and death. [1]
What Should I Do If I Think I Took Too Much Acetaminophen?
If you may have taken more acetaminophen than directed, contact a healthcare professional, poison-control service, or emergency service promptly. Do not wait for symptoms to appear.
Acetaminophen-related liver injury can develop before a person feels seriously ill. Serious liver injury can occur with excessive total daily acetaminophen exposure, especially when multiple acetaminophen-containing products are used. [1]
Conclusion
If you found a tablet marked M523 / 10/325, identification should be treated as only the first step. The labeled U.S. product contains 10 mg of oxycodone hydrochloride and 325 mg of acetaminophen, but matching an imprint, color, or shape cannot prove that an unknown tablet is genuine. From a medication-safety perspective, the most useful details are the complete imprint, strength, pharmacy label, source of the medicine, and whether it was prescribed for the person taking it. Oxycodone can cause respiratory depression, dependence, addiction, and overdose, while excessive acetaminophen can seriously damage the liver. Take the medicine only in the dose and manner prescribed for you, avoid unsafe drug and alcohol combinations, store it securely, and ask a pharmacist whenever an unfamiliar tablet does not match what you expected. [1]
Sources
[1] DailyMed. Oxycodone Hydrochloride and Acetaminophen Tablets — Prescribing Information.
[2] U.S. Food and Drug Administration (FDA). Counterfeit Medicine.
[3] DailyMed. Percocet — Oxycodone Hydrochloride and Acetaminophen Tablets, Prescribing Information.
[4] U.S. Food and Drug Administration (FDA). Access to Naloxone Can Save a Life During an Opioid Overdose.
[5] U.S. Food and Drug Administration, Office of Criminal Investigations. Federal case involving counterfeit pills containing fentanyl.
[6] Drugs.com Pill Identifier. M 523 — Bisoprolol Fumarate 5 mg.
Medical note: This article is for general education only and does not replace advice from a doctor, pharmacist, or other qualified healthcare professional. Do not take an unknown tablet based only on an online description or image.