I'd call a pharmacist. And you don't say what's causing your muscle spasms. It could well be the Celexa, in which case some magnesium citrate will probably take care of the problem, but don't take magnesium at the same time as you take the Celexa. These brain drugs use the magnesium channel to get to the brain, and that can cause muscle spasms -- very common side effect. They also affect serotonin, which is partly responsible for relaxing muscles.