What Is Codeine 300/30 mg?

Codeine 300/30 mg is a combination prescription analgesic containing acetaminophen 300 mg and codeine phosphate 30 mg per tablet. It is classified as a Schedule III controlled substance in the United States, meaning it has a recognized medical use but also a moderate-to-low potential for abuse and dependence.

The “300/30” designation refers to the milligram strength of each active ingredient: 300 mg of acetaminophen and 30 mg of codeine phosphate. This combination is one of the most commonly prescribed opioid/non-opioid analgesic combinations for mild to moderate pain.

What Codeine 300/30 mg Is Prescribed For

Codeine 300/30 mg is FDA-approved for one primary indication:

• Management of mild to moderate pain when other pain treatments such as non-opioid pain medicines do not treat the pain well enough, or when the patient cannot tolerate them.

Important limitation: Codeine should be used at the lowest effective dose for the shortest duration necessary. Adult doses of codeine higher than 60 mg are associated with an increased incidence of adverse reactions and are not associated with greater efficacy.

Active Ingredients

Each tablet contains:

The 300/30 mg tablet is described as a round, white to off-white tablet debossed with “3” on one side and an “M” on the other side.

Available Strengths

Acetaminophen and codeine phosphate combination tablets are available in three strengths:

Dosage Guidelines

Usual Adult Dosage: 1 to 2 tablets every 4 hours as needed for pain.

Maximum Daily Doses:

Key principles:

• Use the lowest effective dosage for the shortest duration consistent with treatment goals

• The prescriber must specify the number of tablets per dose and the maximum number of tablets per 24 hours on the prescription

• Tolerance to codeine can develop with continued use

• Monitor patients closely for respiratory depression, especially within the first 24 to 72 hours of initiating therapy and following dosage increases

Discontinuation: Do not abruptly discontinue in a physically-dependent patient. A gradual taper under medical supervision is required to avoid withdrawal symptoms.

Important Safety Information (Boxed Warning)

Ultra-Rapid Metabolism of Codeine to Morphine: Respiratory depression and death have occurred in children who received codeine following tonsillectomy and/or adenoidectomy and had evidence of being ultra-rapid metabolizers of codeine due to a CYP2D6 polymorphism. Deaths have also occurred in nursing infants exposed to high levels of morphine in breast milk because their mothers were ultra-rapid metabolizers.

Prevalence of Ultra-Rapid Metabolism: This phenotype varies widely and has been estimated at 0.5 to 1% in Chinese and Japanese, 0.5 to 1% in Hispanics, 1–10% in Caucasians, 3% in African Americans, and 16–28% in North Africans, Ethiopians, and Arabs.

Addiction, Abuse, and Misuse: Codeine exposes patients to risks of opioid addiction, abuse, and misuse, which can lead to overdose and death. Even if taken correctly as prescribed, patients are at risk.

Life-Threatening Respiratory Depression: Serious, life-threatening, or fatal respiratory depression may occur, especially during initiation or following a dose increase.

Accidental Ingestion: Accidental ingestion of even one dose, especially by children, can result in a fatal overdose of codeine.

Neonatal Opioid Withdrawal Syndrome: Prolonged use during pregnancy can result in withdrawal in the neonate, which may be life-threatening if not recognized and treated.

Common Side Effects

The most frequently reported adverse reactions include:

• Drowsiness

• Lightheadedness

• Dizziness

• Sedation

• Shortness of breath

• Nausea

• Vomiting

• Constipation

• Abdominal pain

• Pruritus (itching)

• Rash

These effects seem to be more prominent in ambulatory than in non-ambulatory patients, and some may be alleviated if the patient lies down.

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Important Warnings

Respiratory Depression: Codeine produces dose-related respiratory depression by direct action on brain stem respiratory centers. At higher doses, codeine has most of the disadvantages of morphine including respiratory depression.

Interactions with CNS Depressants: Concomitant use of opioids with benzodiazepines, alcohol, or other CNS depressants may result in profound sedation, respiratory depression, coma, and death.

Adrenal Insufficiency: Cases have been reported with opioid use, more often following greater than one month of use.

Severe Hypotension: Codeine may cause severe hypotension. Avoid use in patients with circulatory shock.

Gastrointestinal Effects: Codeine causes a reduction in motility associated with an increase in smooth muscle tone, which may result in constipation. Other opioid-induced effects may include spasm of sphincter of Oddi and transient elevations in serum amylase.

Seizures: Codeine may increase seizure frequency in patients with seizure disorders.

Androgen Deficiency: Chronic use of opioids may influence the hypothalamic-pituitary-gonadal axis, leading to androgen deficiency that may manifest as low libido, impotence, erectile dysfunction, amenorrhea, or infertility.

Drug Interactions

MAOIs (Monoamine Oxidase Inhibitors): Concurrent use or use within 14 days of stopping an MAOI is contraindicated. Risk of hypotension, hyperpyrexia, somnolence, or death.

CNS Depressants (benzodiazepines, alcohol, sedatives): Additive CNS depression. Reserve concomitant prescribing for patients with no alternative options. Limit dosages and durations to the minimum required.

Serotonergic Drugs: Concomitant use may result in serotonin syndrome. Discontinue if suspected.

Mixed Agonist/Antagonist Opioids (buprenorphine, nalbuphine, pentazocine): May reduce analgesic effect or precipitate withdrawal symptoms.

CYP2D6 Inhibitors (fluoxetine, paroxetine, quinidine): May decrease conversion of codeine to morphine, reducing efficacy. After stopping a CYP2D6 inhibitor, morphine levels may increase, potentially causing fatal respiratory depression.

Acetaminophen Interactions: Acetaminophen may interact with oral anticoagulants (warfarin), anticonvulsants (lamotrigine, phenytoin, carbamazepine), antituberculosis drugs (isoniazid, rifampicin), and others. Alcohol may increase the hepatotoxic potential of acetaminophen.

Who Should Not Take Codeine 300/30 mg

Codeine combination products are contraindicated in:

• All children younger than 12 years of age

• Postoperative management in children younger than 18 years of age following tonsillectomy and/or adenoidectomy

• Significant respiratory depression

• Acute or severe bronchial asthma in an unmonitored setting

• Known or suspected gastrointestinal obstruction, including paralytic ileus

• Hypersensitivity to codeine, acetaminophen, or any formulation excipients

• Concurrent use of MAOIs or use within the last 14 days

How Prescriptions Work

As a Schedule III controlled substance, codeine 300/30 mg prescriptions are subject to federal and state regulations:

• Refills: Schedule III prescriptions may be refilled up to 5 times within 6 months from the date written, unless restricted by state law.

• Tapering required: Discontinuation should be gradual in physically-dependent patients. Abrupt discontinuation can precipitate withdrawal symptoms.

• Safe storage: Keep codeine in a secure location out of reach of children. Never share it with others. Selling or giving away codeine is against the law.

• Disposal: Mix unused tablets with an unpalatable substance such as dirt or cat litter, place in a sealed container, and throw in the household trash.

Frequently Asked Questions

Is codeine 300/30 mg safe for long-term use?

Codeine 300/30 mg should be used at the lowest effective dose for the shortest duration necessary. Long-term use increases the risk of dependence, tolerance, and opioid-induced hyperalgesia.

Can I stop taking codeine 300/30 mg suddenly?

No. Abrupt discontinuation in a physically-dependent patient can cause withdrawal symptoms. A gradual taper under medical supervision is required.

Can I drink alcohol while taking codeine 300/30 mg?

No. Alcohol increases the risk of severe side effects from codeine, including decreased blood pressure, seizures, breathing problems, and severe drowsiness. The combination can be fatal. Alcohol also increases the hepatotoxic potential of acetaminophen.

What happens if I take too much codeine 300/30 mg?

Seek emergency help immediately. Signs of overdose include extreme sleepiness, confusion, shallow breathing, pinpoint pupils, and clammy skin. A single or multiple drug overdose with acetaminophen and codeine is a potentially lethal polydrug overdose. Naloxone is a specific antidote for codeine-related respiratory depression.

What is an ultra-rapid metabolizer?

Some individuals have a genetic variation (CYP2D6 polymorphism) that causes them to convert codeine to morphine more rapidly and completely. This can result in life-threatening or fatal respiratory depression even at labeled doses. The prevalence ranges from 0.5% in Chinese and Japanese populations to 16–28% in North Africans, Ethiopians, and Arabs.

Is codeine safe during pregnancy?

Prolonged use during pregnancy can result in neonatal opioid withdrawal syndrome, which may be life-threatening if not recognized and treated. Use only if clearly needed and discuss risks with your healthcare provider.

How does codeine 300/30 mg compare to oxycodone/acetaminophen?

A randomized trial found that codeine/acetaminophen (30 mg/300 mg) provided comparable analgesia to oxycodone/acetaminophen (5 mg/325 mg) for short-term pain management following emergency department discharge, with similar side-effect profiles and patient satisfaction.

How does codeine 300/30 mg compare to aspirin 1000 mg?

Clinical trials for postoperative dental pain and tension-type headache found that aspirin 1000 mg provided statistically significant efficacy compared with placebo and comparable efficacy with acetaminophen 300 mg plus codeine 30 mg.

Conclusion

Codeine 300/30 mg is a Schedule III combination analgesic containing acetaminophen 300 mg and codeine phosphate 30 mg, approved for mild to moderate pain. Its most serious risk is the genetic variability in CYP2D6 metabolism—ultra-rapid metabolizers can experience fatal respiratory depression even at labeled doses, with prevalence ranging from 0.5% to 28% depending on ethnicity. The product is contraindicated in all children under 12 and in children under 18 following tonsillectomy/adenoidectomy. Common side effects include drowsiness, dizziness, nausea, and constipation. Serious risks include respiratory depression when combined with CNS depressants, hepatotoxicity from acetaminophen overdose, adrenal insufficiency, and seizures. The usual adult dose is 1 to 2 tablets every 4 hours as needed, with a maximum of 360 mg codeine and 4,000 mg acetaminophen per 24 hours. Patients should never combine this medication with alcohol or other CNS depressants, store it securely, and never stop treatment abruptly without medical supervision.