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Dextromethorphan

Brand names: Delsym, Robitussin DM, Nyquil (in combination)

Dextromethorphan (DM) quiets a dry, hacking cough from colds.

Brand namesDelsym, Robitussin DM, Nyquil (in combination)
Type of medicineCough suppressant
Prescription?Over the counter
ImportantThis page is general information, not a prescription. Don't start, stop, or change a medicine without talking to your provider or pharmacist.

Overview

It's in many combination cold products. Large amounts are misused, and it can cause serotonin syndrome with some antidepressants.

What it's used for

  • Dry cough from colds

How to take it

  • Follow the label and use the measuring device.
  • Don't give cough and cold medicines to children under 4.
  • Check labels so you don't double up.

Your dose depends on your health and other medicines. Always follow your prescription label, and ask your pharmacist if anything is unclear.

Side effects

Common side effects

  • Dizziness
  • Drowsiness
  • Nausea
Call 911Agitation, fever, sweating, muscle twitching or stiffness, fast heartbeat, and confusion (possible serotonin syndrome)
Call 911Too much: confusion, seeing things, fast heartbeat, or very drowsy. Call Poison Control at 1-800-222-1222 or 911.

Warnings

  • Ask a provider for a cough lasting more than 7 days or with fever, rash, or headache.

Other medicines, foods, and alcohol

  • Never take within 14 days of an MAOI.
  • SSRIs, SNRIs, and other serotonin medicines raise serotonin syndrome risk; fluoxetine, paroxetine, and bupropion also raise its level.
  • Alcohol adds to drowsiness.

Tell your provider and pharmacist about every medicine, vitamin, and supplement you take.

Pregnancy and breastfeeding

Ask your provider before using it in pregnancy.

Missed doses, overdose, and storage

If you miss a dose

This medicine is often taken only when needed. If you take it on a schedule, take a missed dose when you remember, unless it's almost time for the next one. Don't double up.

If someone takes too much

Call Poison Control at 1-800-222-1222 or get help online at poison.org. Call 911 if the person collapses, has a seizure, has trouble breathing, or can't be woken.

Storing it

Store at room temperature, away from heat and moisture (not in the bathroom), and out of reach of children and pets.

Conditions it's used for

Sources

Last updated 2026-11-13.