Here is my problem. For the last 3 months, I have been severely constipated. I am taking 600 mg of gabapentin daily and 1 IP203 Percocet daily, both for pain and neuropathy. I asked my PCP if the gabapentin could be the cause, but he says no. Would either or both meds be causing constipation? I am aware that constipation is a side effect of narcotics, but wonder if 5mg daily is sufficient amount to cause constipation.