Dextromethorphan
Also sold as: Robitussin, Benylin
No prescription neededCough and cold
Comes as:SyrupTablet
Usual adult dose
Usual adult dose: 10 to 20 mg every 4 hours, or 30 mg every 6 to 8 hours, for a dry cough. Do not take more than 120 mg in 24 hours. Not for children under 6 years unless a doctor advises.
Your doctor may give you a different dose. Children's doses depend on weight.
Side effects
Common
- drowsiness
- dizziness
- nausea
- stomach upset
Serious — get help
Stop taking it and see a doctor straight away if you notice:
- confusion
- agitation
- fever and muscle stiffness (serotonin reaction)
- slowed breathing after large doses
Do not take it, or take care, if
- Cough with a lot of phlegm, asthma or COPD (not suitable)
- Taking antidepressants such as fluoxetine or paroxetine
- Liver disease (use with caution)
- Cough lasting more than 2 to 3 weeks needs a doctor (it may be TB or another illness)
Interactions
Medicines that can react with this one.
Serious2 medicinesDo not take these together unless your doctor says so.
- Fluoxetine
Fluoxetine raises dextromethorphan levels and the combination can cause serotonin syndrome.
- Paroxetine
Paroxetine raises dextromethorphan levels and the combination can cause serotonin syndrome.
Moderate1 medicineTake together only with care. Ask your doctor or pharmacist.
- Tramadol
Both increase serotonin and cause drowsiness; the combination is best avoided.