Also, Robaxin is a cousin drug of Skelaxin (a really wonderful muscle relaxer that my insurance won't cover!) My doc also told me that Flexeril is chemically similar to Elavil, which made me gain a bunch of weight. Doctors give trusted answers on uses, effects, side-effects, and cautions: Dr. Elson on flexeril vs robaxin: Skelaxin) is thought to act by suppressing postsynaptic spinal cord and trigeminal reflexes. Flexeril (cyclobenzaprine hcl) is TCA with centrally acting muscle relaxants properties. All the information, content and live chat provided on the site is intended to be for informational purposes only, and not a substitute for professional or medical advice. I was prescribed robaxin first and found it pretty useless- but 750mgs, understand some take 1500mgs, then flexeril- I found a lot of relief at first, but doesn't seem to be working for me as much anymore For the fibro (been on about week and half). Robaxin (methocarbamol) and Flexeril (cyclobenzaprine) are skeletal muscle relaxants. Side effects of Robaxin and Flexeril that are similar include drowsiness, dizziness, headache, nausea, and vomiting. Learn more about side effects, dosage, and pregnancy safety information. This medicine definitely worked for me, however, I felt extremely nauseous, and it gave me headaches. They do NOT make me sleepy. I do not take the 750 mg. 4 times a day as prescribed because of the effects. What is Robaxin. Robaxin (Methocarbamol) is a prescription pills. It used with rest, physical therapy, and other measures to relax muscles and relieve pain and discomfort caused by strains, sprains, and other muscle injuries. Flexeril (cyclobenzaprine) is a muscle relaxant. It works by blocking nerve impulses (or pain sensations) that are sent to your brain. Flexeril is used together with rest and physical therapy to treat skeletal muscle conditions such as pain or injury. Robaxin (methocarbamol) and Flexeril (cyclobenzaprine) are muscle relaxants used together with rest and physical therapy to treat skeletal muscle conditions such as pain or injury. Compare Robaxin vs Skelaxin head-to-head for uses, ratings, cost, side effects, interactions and more. Robaxin rated 6.4/10 vs Skelaxin rated 7.2/10 in overall patient satisfaction. Robaxin rated 6.4/10 vs Skelaxin rated 7.2/10 in overall patient satisfaction.