How much medicine does it take to get a drug overdose?

Morphine HCL = Oral rat LD50: 335 mg/kg. I realize that morphine has no effective top to its painkilling effects, and patients in extreme pain may need to escalate, and therefore must know when safety becomes a problem. Note however that the LD50 of MHCL is so high that it's easy to be safe if you're very careful. I strongly urge you to discuss any dosage changes with your doctor before testing it out yourself. Note also that sub-lethal dosages can increase the chance for respiratory depression to set in. Again -- talk to your doc. Note please I'm not a doctor and a friendly chat with a fellow over the Internet is no substitute for real medical support. This most certainly isn't to be contrued as medical advice.