Dextromethorphan is used to treat a cough. It is available over-the-counter alone and is also present in many over-the-counter and prescription combination medications.
Dextromethorphan will not treat a cough that is caused by smoking, asthma, or emphysema.
Do not give dextromethorphan to a child younger than 4 years old.
Always ask a doctor before giving a cough or cold medicine to a child. Death can occur from the misuse of cough and cold medicines in very young children.
Do not use dextromethorphan if you have used an MAO inhibitor such as isocarboxazid (Marplan), phenelzine (Nardil), rasagiline (Azilect), selegiline (Eldepryl, Emsam), tranylcypromine (Parnate), or methylene blue injection within the past 14 days. Serious, life-threatening side effects can occur if you take dextromethorphan before the MAO inhibitor has cleared from your body.
Do not use any other over-the-counter cough, cold, or allergy medication without first asking your doctor or pharmacist. If you take certain products together you may accidentally take too much of one or more types of medicine. Read the label of any other medicine you are using to see if it contains dextromethorphan. Dextromethorphan will not treat a cough that is caused by smoking, asthma, or emphysema.
Dextromethorphan side effects
Get emergency medical help if you have any of these signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat. Stop using dextromethorphan and call your doctor at once if you have any of these serious side effects:
- severe dizziness, anxiety, restless feeling, or nervousness;
- seizures or convulsions;
- confusion, hallucinations; or
- slow, shallow breathing.
Less serious side effects are more likely, such as stomach upset.
This is not a complete list of dextromethorphan side effects and others may occur. Call your doctor for medical advice about side effects.