M367 – White Oval Pain Pills

Dr. Drew Sutton MD

This article was reviewed and approved by Dr. Drew Sutton MD
Written by Robert Mauer

M367 is a generic combination of hydrocodone and acetaminophen. They are capsule-shaped, white pills embossed with these letters and numbers. On the other side is a groove down the middle for splitting them in half. Mallinckrodt Pharmaceuticals is the manufacturer.

  • Acetaminophen is considered a non-addicting pain reliever.
  • Hydrocodone is a narcotic structure similar to codeine.
  • Opioids convert to morphine in the liver.

People with acute or chronic pain conditions take this medication. For example, these medications are for back pain, rheumatoid arthritis, post-operative pain, discomfort after intensive dental procedures, severe migraines, and osteoarthritis.

Hydrocodone manages pain severe enough to require daily, around-the-clock, long-term treatment and for which alternative treatment options are inadequate. Therefore, it should be prescribed only by healthcare professionals knowledgeable in potent opioids to manage chronic pain.

Caution is necessary, and the patient’s prior analgesic treatment experience must be a factor as the risk for addiction, abuse, and misuse is significant. 

  • Acetaminophen is combined with hydrocodone because it increases the  effectiveness of both (potentiates).

Other brand names for acetaminophen hydrocodone combination drugs include;

  • Vicodin
  • Lortab
  • Norco
  • Lorcet
  • Zydone
  • Stages
  • Xodol

The dosage limit allows for no more than 325 mg per unit for prescription medications that contain acetaminophen. Therefore, each pill contains 325 mg of acetaminophen. The amount of hydrocodone in each M367 pill is 10 mg.

They are categorized as Schedule II controlled substances by the Federal Drug Enforcement Agency because of their high risk for abuse and addiction.

Hydrocodone targets the opioid receptors in the brain.

  • The duration of the effects of the pill is approximately four to eight hours.
  • It takes only about 15 to 20 minutes to reach its peak effect.

As tolerance builds, users will experience longer times to feel its effects and “come down” from hydrocodone faster. Opioid tolerance is receiving the following opioids (or an equivalent dose of another opioid) for one week or longer.

According to the U.S. Department Of Justice: “Hydrocodone is the most frequently prescribed opiate in the United States with more than 136 million prescriptions for hydrocodone-containing products dispensed in 2013 and with nearly 65.5 million dispensed in the first six months of 2014.”

Because of the risks of addiction, abuse, and misuse as opioids, even at recommended doses, and because of the more significant dangers of overdose and death with extended-release opioid formulations, hydrocodone should be used with extreme caution.

The most common side effects are:

  • constipation
  • nausea
  • vomiting
  • somnolence
  • headache
  • dizziness

More severe side effects may occur in some cases, especially when too many pills in 24 hours. These effects include:

  • Difficulty breathing
  • Allergic reactions (swelling of the tongue, lips, and face)
  • Hives and itchy rash
  • Feeling fearful, depressed, and or anxious
  • Sudden mood swings
  • Inability to urinate
  • Muscle tremors

Hydrocodone can cause serious drug interactions. Therefore it is never combined with alvimopan, a medication used for recovery after small or large bowel resection. Examples of other possible serious drug interactions include, but are not limited to:

  • alprazolam
  • amobarbital
  • buspirone
  • butalbital
  • clonidine
  • codeine
  • ethanol
  • fentanyl
  • lorazepam
  • methadone

Hepatotoxicity may occur with acetaminophen doses that exceed four g/day. Therefore, always consider all acetaminophen-containing products the patient is taking, including PRN doses and OTC products.

  • Acetaminophen may cause acute liver failure, at times resulting in liver transplantation or death.

When hydrocodone stimulates opioid receptors, it causes a “rush” of dopamine and serotonin to flood the brain. These neurotransmitters activate the “feel good” areas, giving us the euphoric, pleasant sensations indicative of an opioid drug. If someone abuses or takes this drug for an extended period, the brain grows accustomed to having excess dopamine and serotonin, activating its reward centers. Conversely, when levels of these neurotransmitters decrease, the brain initiates severe cravings for more.

  • It is easy to overdose because it interferes with the perception of time. In most cases, overdoses happen when the user forgets how many they have taken in what amount of time.

Opioid analgesic risk evaluation and mitigation strategy (REMS)

To ensure the benefits of opioid medication outweigh the risks of addiction, abuse, and misuse, the FDA requires a REMS for these products.

As tolerance builds to the drug, the pain returns faster than it should, making the user think it is time to take another pill. Signs of a possible overdose include:

  • Inability to stay awake
  • Excessive perspiration
  • Slowed pulse rate or irregular heartbeat
  • Shallow breathing
  • Blood in the urine
  • Chest pain
  • Clammy skin

If an overdose is suspected, the victim needs immediate emergency treatment to provide supportive care.


The (DSM-5) defines opioid use disorder as a problematic pattern of opioid use leading to clinically significant impairment or distress, as manifested by at least two of the following, occurring within 12 months: 

  • Taking more significant amounts of opioids or taking opioids over a more extended period than was intended
  • Experiencing a persistent desire for the opioid or engaging in unsuccessful efforts to cut down or control opioid use.
  • Spending a great deal of time in activities necessary to obtain, use, or recover from the effects of the opioid.
  • Craving, or a strong desire or urge to use opioids.
  • Using opioids in a fashion results in a failure to fulfill significant role obligations at work, school, or home.
  • Continuing to use opioids despite experiencing persistent or recurrent social or interpersonal problems caused or exacerbated by the effects of opioids.
  • Giving up or reducing important social, occupational, or recreational activities because of opioid use.
  • Continuing to take opioids in situations in which it is physically hazardous.
  • Continuing to use opioids despite knowledge despite having persistent or recurrent physical or psychological problems likely caused or exacerbated by the substance.
  • Tolerance, as defined by either a need for markedly increased amounts of opioids to achieve intoxications or desired effect or a markedly diminished effect with continued use of the same dose of an opioid.
  • Withdrawal, as manifested by either the characteristic opioid withdrawal syndrome or taking opioids to relieve or avoid withdrawal symptoms.

Treating hydrocodone addiction requires medical detoxification, psychological counseling, and medications. In addition, people addicted to hydrocodone should never attempt to go “cold turkey” due to serious health issues arising from abrupt withdrawal.


The American Psychiatric Association (APA) guidelines identify the following treatment modalities as effective strategies for managing opioid dependence and withdrawal.

  • opioid substitution with methadone or buprenorphine, followed by a gradual taper
  • abrupt opioid discontinuation with the use of clonidine to suppress withdrawal symptoms
  • clonidine-naltrexone detoxification

The APA guidelines recommend the following evidence-based psychosocial treatments for opioid use disorder: 

  • behavioral therapies (e.g., community reinforcement, contingency management)
  • cognitive-behavioral therapies (CBTs) (e.g., relapse prevention, social skills training)
  • psychodynamic therapy/interpersonal therapy (IPT)
  • group and family therapies


  • The International Narcotics Control Board reported that in 2015, Americans represented about 99.7% of the world’s hydrocodone consumption.
  • Between 2007 and 2016, the most widely prescribed opioid was hydrocodone (brand name Vicodin).
  • In 2016, 6.2 billion hydrocodone pills nationwide. The second most prevalent opioid was oxycodone (Percocet).
  • In 2016, 5 billion oxycodone tablets were prescribed in the United States.
  • According to the CDC, from 1999 to 2016, more than 200,000 people died in the United States from overdoses related to prescription opioids.
  • Overdose deaths involving prescription opioids were five times higher in 2016 than in 1999.
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