Does Darvon (propoxyphene) cause side effects?

Darvon (propoxyphene) is a narcotic pain reliever and cough suppressant used to relieve mild to moderate pain.

The precise mechanism of action is not known but may involve stimulation of opioid (narcotic) receptors in the brain. It is weaker than morphine, codeine, and hydrocodone.

Darvon increases pain tolerance and decreases discomfort but the presence of pain still is apparent. In addition to pain reduction, Darvon also causes sedation and respiratory depression

Common side effects of Darvon include

Serious side effects of Darvon include

Darvon may be habit-forming. Mental and physical dependence can occur but are unlikely when used for short-term pain relief.

Drug interactions of Darvon include drugs that slow brain function because Darvon increases the effect of these drugs, such as

Combined use of muscle relaxants and Darvon may lead to increased respiratory depression.

Combining Darvon with carbamazepine may have extreme effects on the brain, including coma.

Since Darvon causes constipation, the use of antidiarrheals in persons taking Darvon can lead to severe constipation.

Drugs that both stimulate and block opioid receptors, may reduce the effect of Darvon and may precipitate Darvon withdrawal symptoms, such as

The metabolism of Darvon may be altered by strong CYP3A4 inhibitors, leading to enhanced Darvon plasma levels, such as

There are no adequate studies of Darvon in pregnant women. Low concentrations of Darvon have been measured in breast milk. It is unknown if these small amounts can cause side effects in nursing infants. Consult your doctor before breastfeeding.

What are the important side effects of Darvon (propoxyphene)?


There have been numerous cases of accidental and intentional overdose with propoxyphene products either alone or in combination with other CNS depressants, including alcohol.

Fatalities within the first hour of overdosage are not uncommon.

Many of the propoxyphene-related deaths have occurred in patients with previous histories of emotional disturbances or suicidal ideation/attempts and/or concomitant administration of

  • sedatives,
  • tranquilizers,
  • muscle relaxants,
  • antidepressants, or
  • other CNS-depressant drugs.

Do not prescribe propoxyphene for patients who are suicidal or have a history of suicidal ideation.

Common side effects

The most frequent adverse reactions of propoxyphene include: 

Other side effects include

  • drowsiness,
  • constipation, and
  • spasm of the ureter, which can lead to difficulty in urinating.

Propoxyphene can depress breathing and should be used with caution in elderly, debilitated patients and in patients with serious lung disease.

Propoxyphene can impair thinking and the physical abilities required for driving or operating machinery.

Propoxyphene may be habit forming. Mental and physical dependence can occur but are unlikely when used for short-term pain relief.

Darvon (propoxyphene) side effects list for healthcare professionals

In hospitalized patients, the most frequently reported were

  • dizziness,
  • sedation,
  • nausea, and
  • vomiting.

Other adverse reactions include

The most frequently reported postmarketing adverse events have included

  • completed suicide,
  • accidental and intentional overdose,
  • drug dependence,
  • cardiac arrest,
  • coma,
  • drug ineffective,
  • drug toxicity,
  • nausea,
  • respiratory arrest,
  • cardio-respiratory arrest,
  • death,
  • vomiting,
  • dizziness,
  • convulsion,
  • confusional state, and
  • diarrhea.

Additional adverse experiences reported through postmarketing surveillance include:

Cardiac disorders: arrhythmia, bradycardia, cardiac/respiratory arrest, congestive arrest, congestive heart failure (CHF), tachycardia, myocardial infarction (MI)

Eye disorder: eye swelling, vision blurred

General disorder and administration site conditions: , drug interaction, drug tolerance, drug withdrawal syndrome

Gastrointestinal disorder: gastrointestinal bleed, acute pancreatitis

Hepatobiliary disorder: hepatic steatosis, hepatomegaly, hepatocellular injury

Immune system disorder: hypersensitivity

Injury poisoning and procedural complications: drug toxicity, hip fracture, multiple drug overdose, narcotic overdose

Investigations: blood pressure decreased, heart rate elevated/abnormal

Metabolism and nutrition disorder: metabolic acidosis

Nervous system disorder: ataxia, coma, dizziness, somnolence, syncope

Psychiatric: abnormal behavior, confusional state, hallucinations, mental status change

Respiratory, thoracic, and mediastinal disorders: respiratory depression, dyspnoea

Skin and subcutaneous tissue disorder: rash, itch

Liver dysfunction has been reported in association with Darvon. Propoxyphene therapy has been associated with abnormal liver function tests and, more rarely, with instances of reversible jaundice (including cholestatic jaundice).

Subacute painful myopathy has been reported following chronic propoxyphene overdosage.

Does Darvon (propoxyphene) cause addiction or withdrawal symptoms?

Drug Abuse And Dependence

Controlled Substance
  • Darvon (propoxyphene) is a Schedule IV narcotic under the U.S. Controlled Substances Act. Darvon (propoxyphene) can produce drug dependence of the morphine type, and therefore, has the potential for being abused.
  • Psychic dependence, physical dependence and tolerance may develop upon repeated administration.
  • Darvon (propoxyphene) should be prescribed and administered with the same degree of caution appropriate to the use of other narcotic-containing medications.
  • Since Darvon (propoxyphene) is a mu-opioid agonist, it may be subject to misuse, abuse, and addiction.
  • Addiction to opioids prescribed for pain management has not been estimated.
  • However, requests for opioids from opioid-addicted patients occur. As such, physicians should take appropriate care in prescribing Darvon (propoxyphene) .
  • Opioid analgesics may cause psychological and physical dependence.
  • Physical dependence results in withdrawal symptoms in patients who abruptly discontinue the drug after long term administration.
  • Also, symptoms of withdrawal may be precipitated through the administration of drugs with mu-opioid antagonist activity, e.g., naloxone or mixed agonist/antagonist analgesics (pentazocine, butorphanol, nalbuphine, dezocine).
  • Physical dependence usually does not occur to a clinically significant degree, until after several weeks of continued opioid usage.
  • Tolerance, in which increasingly larger doses are required to produce the same degree of analgesia, is initially manifested by a shortened duration of an analgesic effect and subsequently, by decreases in the intensity of analgesia.
  • In chronic pain patients, and in opioid-tolerant cancer patients, the administration of Darvon (propoxyphene) should be guided by the degree of tolerance manifested and the doses needed to adequately relieve pain.

The severity of the Darvon (propoxyphene) abstinence syndrome may depend on the degree of physical dependence.

  • Withdrawal is characterized by rhinitis, myalgia, abdominal cramping, and occasional diarrhea.
  • Most observable symptoms disappear in 5 to 14 days without treatment; however, there may be a phase of secondary or chronic abstinence which may last for 2 to 6 months characterized by insomnia, irritability, and muscular aches.
  • The patient may be detoxified by gradual reduction of the dose. Gastrointestinal disturbances or dehydration should be treated with supportive care.

What drugs interact with Darvon (propoxyphene)?

Drug Interactions with Propoxyphene

Propoxyphene is metabolized mainly via the human cytochrome P450 3A4 isoenzyme system (CYP3A4), therefore potential interactions may occur when propoxyphene is administered concurrently with agents that affect CYP3A4 activity.

  • The metabolism of propoxyphene may be altered by strong CYP3A4 inhibitors (such as ritonavir, ketoconazole, itraconazole, troleandomycin, clarithromycin, nelfinavir, nefazadone, amiodarone, amprenavir, aprepitant, diltiazem, erythromycin, fluconazole, fosamprenavir, grapefruit juice, and verapamil) leading to enhanced propoxyphene plasma levels.
  • Coadministration with agents that induce CYP3A4 activity may reduce the efficacy of propoxyphene.
  • Strong CYP3A4 inducers such as rifampin may lead to enhanced metabolite (norpropoxyphene) levels.
  • Propoxyphene is also thought to possess CYP3A4 and CYP2D6 enzyme inhibiting properties and coadministration with drugs that rely on either of these enzymes for metabolism may result in increased pharmacologic or adverse effects of that drug.
  • Severe neurologic signs, including coma, have occurred with concurrent use of carbamazepine (metabolized by CYP3A4).
  • Increased risk of bleeding has been observed with warfarin-like agents when given along with propoxyphene; however, the mechanistic basis of this interaction is unknown.
CNS Depressants
  • Patients receiving narcotic analgesics, general anesthetics, phenothiazines, other tranquilizers, sedative-hypnotics or other CNS depressants (including alcohol) concomitantly with propoxyphene may exhibit an additive CNS depression.
  • Interactive effects resulting in respiratory depression, hypotension, profound sedation, or coma may result if these drugs are taken in combination with the usual dosage of Darvon (propoxyphene).
  • When such combined therapy is contemplated, the dose of one or both agents should be reduced.
Mixed Agonist/Antagonist Opioid Analgesics
  • Agonist/antagonist analgesics (i.e., pentazocine, nalbuphine, butorphanol and buprenorphine) should be administered with caution to patients who have received or are receiving a course of therapy with a pure opioid agonist analgesic such as Darvon (propoxyphene).
  • In this situation, mixed agonist/antagonist analgesics may reduce the analgesic effect of Darvon (propoxyphene) and/or may precipitate withdrawal symptoms in these patients.
Monoamine Oxidase Inhibitors (MAOIs)
  • MAOIs have been reported to intensify the effects of at least one opioid drug causing anxiety, confusion and significant depression of respiration or coma.
  • The use of Darvon (propoxyphene) is not recommended for patients taking MAOIs or within 14 days of stopping such treatment.

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Medically Reviewed on 6/29/2020
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Professional side effects, drug interactions, and addiction sections courtesy of the U.S. Food and Drug Administration.