Nevermind, I found this in some random DXM faq.

************************** TOXICOLOGY INFORMATION ****************************

TOXICOLOGY:
Oral TDLo (child): 30 mg/kg (central nervous system effects) (SAX)
Oral LD50 (rat): 350 mg/kg (RTECS)
Oral LD50 (mouse): 165 mg/kg (RTECS)
Subcutaneous LD50 (rat): 423 mg/kg (RTECS)
Subcutaneous LD50 (mouse): 153 mg/kg (RTECS)
Intravenous LD50 (mouse): 34 mg/kg (RTECS)

If you don't know what LD50 is, find out. Know your drug before you take it.
lateralus Reviewed by lateralus on . tussin how much does it take to 'overdose' on cough medicine? Rating: 5