I must add this fact to mcd's entry: it is dangerous to use tramadol with marijuana and certain other drugs. Tramadol lowers the seizure threshold because it is part serotonin-reuptake inhibitor, and cannabis adds to that effect. I myself had a myoclonic (myoclonus) seizure from combining these two drugs. It is also worth noting that the same goes for combining any two drugs that have an antidepressant effect -- such as tramadol plus an antidepressant. The condition that occurs from too much serotonin in synapses is called Serotonin Syndrome.