I know that you can die if you take any product with DXM while you are currently taking an MAOI (Monoamine Oxidase Inhibitor).

A more detailed explanation from Erowid.org

Do not take DXM if you are using, or have used an MAO Inhibitor within the last 2 weeks.
MAOI's include harmine & harmaline, as well as many anti-depressants.
Check with a doctor if you're unsure whether you medication contains MAOI's.
When combined with MAOI's, DXM can cause "serotonin syndrome" with fever, hypertension, and arrhythmias.


Do not take DXM if you are using, or have used an SSRIs within the last 2 weeks.

SSRIs include many anti-depressants, including Fluoxetine (Prozac), Citalopram (Celexa, Lexapro), Paroxetine (Paxil), and others.
Check with a doctor if you're unsure whether you medication is an SSRI.
When combined with SSRIs, DXM may cause "serotonin syndrome" with fever, hypertension, arrhythmias, etc.
References: Bowdle TA. "Adverse effects of opioid agonists and agonist-antagonists in anaesthesia." Drug Saf. 19(3):173-189. 1998 Sep; Bernard SA, Bruera E. "Drug interactions in palliative care." J Clin Oncol. 2000 Apr;18(8):1780-99.;