Dextromethorphan (AKA Dex, Skittles, Syrup, DXM, Robo, Tussin) is a legal, over-the-counter, semisynthetic narcotic available in many cough suppressants in the United States and most countries. Any drug name with DM or Tuss in it contains the drug.

What does it look like? DXM comes in many different forms. The most common are various over-the-counter cough suppressants (including Robitussin, Delsym, Pertussin, Drixoral, Vicks formula 44, and several generic brands). Each brand contains different quantities of dextromethorphan, generally in the 20-30 mg per capsule range.

How is it used?

Swallowed.

What are its short-term effects?

Symptoms of an overdose include flushing, sweating, nausea, vomiting, diarrhea, abdominal pain, seizures, confusion, high blood pressure (headache, redness of face, blurred vision), an irregular heartbeat, numbness of fingers or toes, hyperactivity, and hallucinations.

Source: US National Library of Medicine