Soma and Robaxin differ in their chemical makeup and generic names. Soma is the brand name for carisoprodol, and Robaxin is the generic name for methocarbamol. Both drugs are muscle relaxants that work by blocking pain receptors in the brain. Soma may be habit-forming, according to Drugs.com.
Robaxin is synthesized from guaifenasin, an expectorant drug used to bring up phlegm from the respiratory tract. Soma is synthesized from a chloroformate drug commonly used as an anesthetic.
Both Soma and Robaxin are used in combination with physical therapy to treat physical injuries and musculoskeletal abnormalities. Both drugs can be habit-forming and cause withdrawal symptoms if not taken as prescribed. Side effects for Soma and Robaxin include drowsiness, dizziness, headache, blurred vision and insomnia. These side effects disappear as the body gets used to taking the medication, according to Drugs.com.
Alcohol, cold medicine, sleeping pills and anti-anxiety medications can increase the drowsiness and dizziness associated with taking these medications. Serious side effects or symptoms of overdose require medical attention. Such symptoms include confusion, difficulty breathing, hallucinations and loss of consciousness. Withdrawal symptoms, such as nausea, stomach cramps and headache, can occur if these medications are stopped abruptly. Physicians gradually reduce the dose of these medications to prevent withdrawal.