Nefopam – Side Effects and Dosage

What is Nefopam?

Nefopam is a painkiller which is prescribed to relieve moderate pain which is not being controlled by other painkillers such as paracetamol or aspirin. Although it is not fully understood how it works, it is thought to interrupt the way pain messages are sent to your brain from your body. This means you feel less pain. It is only available on prescription.

Properties and Characteristics of Nefopam

Drug class Analgesics
Brand Names Acupan, Acupainlex Panbiotic, Nefalgic, Nefomed, Nopain, Nefomax
Synonyms Nefopam, 13669-70-0, Fenazoxine
Molecular Formula C17H19NO
Molecular Weight 253.34 g/mol
IUPAC Name 5-methyl-1-phenyl-1,3,4,6-tetrahydro-2,5-benzoxazocine
Structural formula of main components
Pure active ingredient Nefopam hydrochloride
Appearance Crystalline powder
Melting point 245-250°C (dec.)
Solubility H2O: 5 mg/mL, clear
Excretion Nefopam is excreted mainly in urine
Storage Store at 4° C
Available Forms Tablet and Solution
Prescription   Doctor prescription is required

Uses of Nefopam

  • Nefopam has been investigated for the prevention of Kidney Transplantation
  • Non-narcotic analgesic is chemically similar to orphenadrine. It is used for the relief of acute and chronic pain
  • It was significantly more effective than aspirin as an analgesic in one clinical trial, although with a greater incidence of side effects such as sweating, dizziness, and nausea, especially at higher doses
  • The estimated relative potency of nefopam to morphine indicates that 20 mg of nefopam HCl is the approximate analgesic equal of 12 mg of morphine with comparable analgesic efficacy to morphine, or oxycodone, while nefopam tends to produce fewer side effects, does not produce respiratory depression and has much less abuse potential, and so is useful either as an alternative to opioid analgesics or as an adjunctive treatment for use alongside opioids or other types of analgesics
  • It is also used to treat severe hiccups

Side effects

Common side effects

Like all medicines, nefopam can give you side effects. However, many people have no side effects at all.

Talk to your doctor or pharmacist if these side effects bother you or do not go away:

  • Feeling sick (nausea)
  • Feeling dizzy or lightheaded
  • Feeling nervous, confused or shaky
  • A dry mouth
  • Difficulty peeing
  • Seeing things that are not there (hallucinations)
  • Numbness or tingling in your hands and feet

It may also colour your pee pink. But do not worry, this is harmless.

If you are aged over 65 years, you may be more likely to get some side effects, such as feeling confused or having hallucinations.

Serious allergic reaction: In rare cases, it’s possible to have a serious allergic reaction (anaphylaxis) to nefopam.

Mechanism of action

Nefopam (nefopam-hydrochloride) is a potent, rapidly-acting non-narcotic analgesic. It is totally distinct from other centrally-acting analgesics such as morphine, codeine, pentazocine, and propoxyphene. Unlike the narcotic agents, nefopam has been shown not to cause respiratory depression. It is indicated for the relief of acute and chronic pain, including post operative pain, dental pain, Musculoskeletal pain, acute traumatic pain and cancer pain. Its mechanism of action is unclear.

Drug Interactions

Nefopam is a non-opioid pain reliever with relatively low interaction risks. Consult your healthcare provider for personalized advice, but here are key interactions:

  • Serotonin Syndrome Risk: Nefopam can raise serotonin levels, potentially causing serotonin syndrome when combine with SSRIs, SNRIs, or certain antidepressants. Symptoms include confusion, hallucinations, rapid heart rate, fever, and muscle stiffness. Use cautiously under medical supervision.
  • MAO Inhibitors: Mixing it with MAOIs (antidepressants) can lead to severe side effects like dangerously high blood pressure.
  • Central Nervous System Depressants: Nefopam may intensify sedation when taken with alcohol, benzodiazepines, or certain sleep medications. This can result in excessive drowsiness, impaired coordination, and increased accident risk.
  • Anticholinergic Drugs: Combining nefopam with anticholinergic medications (e.g., some antihistamines, antipsychotics, and tricyclic antidepressants) may lead to side effects like dry mouth, constipation, and urinary issues.
  • Other Pain Medications: Using nefopam with opioids or NSAIDs may enhance pain relief, but this should be closely managed by a healthcare provider to avoid potential side effects.
  • CYP2D6 Inhibitors: Nefopam is metabolized by the CYP2D6 enzyme. Medications inhibiting this enzyme (e.g., some antidepressants and antipsychotics) may affect nefopam’s metabolism and effectiveness.

Inform your healthcare provider about all medications, supplements, and OTC drugs you take for a thorough risk assessment. Individual responses vary, so personalized advice is crucial when using nefopam or any medication.



  • Dose range is 30 mg to 90 mg, three times daily depending on response
  • Recommended starting dose: 60 mg, three times per day, adjusting according to response


  • Due to reduced metabolism and increased susceptibility to CNS effects, dosage reduction is advised.
  • Starting dose: 30 mg three times per day

Children over 12

  • Dose range is 30 mg to 90 mg, three times daily depending on response
  • Recommended starting dose: 60 mg, three times per day, adjusting according to response


Like any medication, it’s essential to take Nefopam as prescribed by a healthcare professional to avoid potential overdose. If someone takes more than the recommended dose of it, it can lead to an overdose, which can have various symptoms. Overdose symptoms may include:

Nefopam overdose can result in various symptoms, including:

  • Nervous system effects like confusion, agitation, and hallucinations.
  • Cardiovascular symptoms like rapid heart rate and low blood pressure.
  • Gastrointestinal issues such as nausea and vomiting.
  • Respiratory problems or muscle rigidity in severe cases.

If you suspect a overdose, seek immediate medical attention. It’s crucial to take medications as prescribed to prevent overdose and associated risks.

Warnings and precautions

Talk to your doctor or pharmacist before taking Nefopam Tablets if:

  • You have severe problems with your liver or kidneys
  • You have, or have had in the past difficulty passing urine
  • You have problems with your heart
  • You were previously diagnosed with glaucoma (increased pressure in the eye).


Nefopam Tablets are NOT recommended for children under 12 years old

Pregnancy and breastfeeding

Nefopam and pregnancy

Nefopam is not usually recommended during pregnancy. This is because there’s little information to know how the medicine might affect your baby.

Paracetamol is generally the first choice of painkiller for pregnant women. Stronger painkillers are available which can be used in pregnancy after discussion with your doctor.

Talk to your doctor who will advise you about the most suitable medicine for you and your baby.

Nefopam and breastfeeding

Nefopam passes into breast milk in very small amounts but it is unlikely to harm your baby so you can continue breastfeeding if your doctor says you need to take it.

If you notice that your baby is not feeding as well as usual, or if you have any other concerns about your baby, talk to your health visitor, midwife, pharmacist or doctor as soon as possible.

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