Short answer: Dextromethorphan (DXM) is the cough suppressant in many over-the-counter medicines, such as Delsym, Robitussin DM, and NyQuil. It is safe at label doses, but at high doses it acts as a dissociative drug like ketamine. Misuse can cause psychosis, serotonin syndrome, and poisoning from other ingredients such as acetaminophen.
Key takeaways
- What it is: Dextromethorphan is a cough suppressant; nmda receptor antagonist at high doses and not a federally controlled substance.
- Main uses: Cough; depression (with bupropion); pseudobulbar affect (with quinidine).
- Timing: effects start in 15 to 30 minutes and last 3 to 6 hours (longer at high doses).
- Most dangerous mix: MAO inhibitors (within 14 days), which can cause serotonin syndrome, high fever, death.
- Naloxone: it does not reverse this drug, but give it whenever opioids could be involved.
- Dependence risk: Low; moderate with misuse.
- Legal route: sold without a prescription; follow the Drug Facts label.
What is dextromethorphan?
Dextromethorphan quiets the cough reflex in the brain. It is in more than 100 over-the-counter cough and cold products.
In 2022 the FDA approved Auvelity, which combines dextromethorphan with bupropion, as a rapid-acting treatment for major depression. Nuedexta, with quinidine, treats pseudobulbar affect, uncontrollable laughing or crying after brain injury.
Quick facts
| Fact | Dextromethorphan |
|---|---|
| Generic name | Dextromethorphan hydrobromide |
| Brand names | Delsym, Robitussin DM, Mucinex DM, NyQuil, Coricidin HBP; prescription: Auvelity, Nuedexta |
| Drug class | Antitussive; NMDA receptor antagonist and sigma-1 agonist; serotonin reuptake inhibitor |
| US legal status | Over the counter; not federally controlled; age limits in many states |
| Approved uses | Cough; major depression (Auvelity); pseudobulbar affect (Nuedexta) |
| Maximum OTC dose | 120 mg in 24 hours for adults |
| Onset | 15 to 30 minutes |
| Broken down by | CYP2D6 to dextrorphan |
How long does dextromethorphan last?
- Starts working: 15 to 30 minutes
- Effects last: 3 to 6 hours (longer at high doses)
Timing varies with the dose, the form, how it is taken, liver and kidney function, age, and other drugs taken at the same time.
What are the biggest risks of dextromethorphan?
Common side effects at label doses include dizziness, drowsiness, and nausea.
High doses: large amounts cause dissociation, hallucinations, confusion, loss of coordination, fast heartbeat, high blood pressure, and psychosis.
Other ingredients: taking high doses of combination products can cause acetaminophen liver failure or, with Coricidin's chlorpheniramine, seizures and heart problems.
What should you never mix with dextromethorphan?
| Combined with | What happens | Guidance |
|---|---|---|
| MAO inhibitors (within 14 days) | Serotonin syndrome, high fever, death | Contraindicated |
| SSRIs, SNRIs, tramadol, triptans | Serotonin syndrome | Use caution |
| Fluoxetine, paroxetine, bupropion, quinidine (CYP2D6 inhibitors) | Much higher dextromethorphan levels | Use caution |
| Alcohol, opioids, sedatives | More sedation and impairment | Avoid |
| Ketamine or other dissociatives | Profound confusion and unconsciousness | Dangerous |
Check any combination with the DoseUses combination checker or ask a pharmacist.
What are the signs of a dextromethorphan overdose, and what should you do?
Overdose causes agitation, hallucinations, dissociation, fast heartbeat, high blood pressure, high temperature, vomiting, and, with serotonergic drugs, serotonin syndrome. Products with acetaminophen can cause delayed liver failure.
If someone is having a dangerous reaction
- Call 911 for a seizure, chest pain, a very high temperature, trouble breathing, unresponsiveness, or if the person may harm themselves or others.
- Move them to a quiet, safe place away from roads, water, heights, and crowds. Stay with them and speak calmly.
- Do not leave the person alone and do not give them other drugs or alcohol to calm them down.
- If they become unresponsive, place them on their side and give naloxone in case opioids are involved.
Is dextromethorphan addictive?
Label doses are not addictive. People who repeatedly take high doses can develop tolerance, cravings, and compulsive use.
- Days 1 to 3Come-downLow mood, fatigue, insomnia, and restlessness after heavy use.
- Week 1WithdrawalCravings, irritability, and poor concentration.
- WeeksRecoverySymptoms ease; memory and mood problems may linger after long-term heavy use.
See the withdrawal timelines and the full dextromethorphan withdrawal guide.
Is dextromethorphan legal?
Dextromethorphan is sold over the counter. It is not a federal controlled substance.
- Age limits: about 20 states, including California, Florida, New York, and Texas, ban sales to anyone under 18 without a prescription, and many retailers check ID nationwide.
- Prescription forms: Auvelity and Nuedexta require a prescription.
- Cost: generic OTC dextromethorphan is inexpensive.
Outside the United States
| Country | Status |
|---|---|
| United Kingdom | Pharmacy medicine |
| Canada | Non-prescription medicine |
| International | Not under UN control |
Frequently asked questions about dextromethorphan
What is robotripping?
Taking very high doses of DXM cough medicine to get a dissociative high. It can cause psychosis and dangerous poisoning.
Can you take DXM with an antidepressant?
Not with MAO inhibitors, and only with caution with SSRIs and SNRIs because of serotonin syndrome.
Why do I need ID to buy cough medicine?
Many states ban sales of DXM to people under 18 to reduce teen misuse.
Is dextromethorphan an opioid?
No. It is chemically related to opioids but does not act on opioid receptors at normal doses.
What is Auvelity?
A prescription combination of dextromethorphan and bupropion approved in 2022 for major depression.
Sources
- Delsym (dextromethorphan) prescription information, DailyMed, US National Library of Medicine.
- Auvelity (dextromethorphan and bupropion) prescription information, DailyMed, US National Library of Medicine.
- Over-the-Counter Medicines DrugFacts, National Institute on Drug Abuse.
- BeSafeRx: Your Source for Online Pharmacy Information, US Food and Drug Administration.
- International drug control conventions, United Nations Office on Drugs and Crime.
This guide summarizes the sourced DoseUses Dextromethorphan profile, written from FDA labels, DEA rules, and federal health agencies. It is educational and is not medical advice. Last updated October 5, 2026.
