I started onfi and my hamstrings are tight and sore, so is my sacrum area. Is this a bad side effect? ## Onfi contains the active ingredient Clobazam, it's most commonly used to treat seizures associated with Lennox-Gastaut Syndrome, it is a benzodiazepine, so it may be habit forming and could cause side effects, such as nausea, dizziness, headache and irritability. And yes, it can also cause muscle pain and stiffness as a side effect. If it is very severe, you should consult your doctor. Is there anything else I can help with? ## no more pain