muscle spasm
"I have herniated disks L5 and between C3 and C4. I got a prescription for Carisoprodol and pain killers. Kept the Carisoprodol for a while because I didn't use it. Had a recent spasm in my neck and used two 10mg pills over one day. I was able to really see the effects of just these two pills because I was taking no other drugs at this time. 
Effects: Next day muscle spasm has subsided significantly. Didn't take more.
Side effects: Lethargy. Took an hour nap and it wasn't enough. I never nap. Went to bed early, got up late. Breathing was labored upon waking. Slight headache in the morning, a bit drowsy, slightly dizzy and unenthusiastic about life."