Every year, emergency departments see patients from DXM-related complications that were entirely preventable. This guide exists to keep you out of that statistic.
The Most Important Thing You Can Do: Check Your Medications
Before anything else — before choosing a dose, before buying a product, before thinking about set and setting — check every medication and supplement you currently take against the DXM interaction database. The most dangerous DXM-related events are not overdoses. They are serotonin syndrome from combining DXM with antidepressants.
SSRIs, SNRIs, MAOIs, tramadol, triptans, lithium — all of these create potentially fatal interactions with DXM. If you take any of these medications, DXM is not safe for you. Full stop.
Verify Your Product
Not all cough syrups are created equal. Many “DXM” products contain additional active ingredients that are safe at therapeutic doses but dangerous at recreational doses:
- Acetaminophen (Tylenol, APAP): At high doses, acetaminophen is toxic to the liver. Products containing acetaminophen and DXM are dangerous at recreational doses.
- Guaifenesin: An expectorant. At high doses causes severe nausea and vomiting. Won’t kill you but will ruin your evening.
- Chlorpheniramine (CPM): An antihistamine. Combined with DXM at high doses can cause dangerous anticholinergic effects.
Look for products containing ONLY dextromethorphan as the active ingredient.
Dose by Weight
DXM dosing is not one-size-fits-all. Dose is calculated per kilogram of body weight. A 90kg person needs significantly more DXM than a 55kg person to reach the same plateau. Use the calculator on this site — it takes your weight and target plateau and gives you a specific range.
Start Low
If it’s your first time, start at the lowest effective dose. The drug will still be there next time. There is nothing to be gained by going deep on your first experience with a substance your body has never encountered. Find out how you personally respond before escalating.
Have Support
A sober person who knows what you’ve taken and can call for help is not optional at 2nd plateau and above. The value of a tripsitter is not that they do anything dramatic — it’s that they provide a reference point in reality and can call emergency services if something goes wrong.