Do not use if you are pregnant, breastfeeding or have scleroderma. Consult a healthcare practitioner prior to use if you are taking carbidopa or drugs/supplements with serotonergic activity. These may include, but are not limited to, L-tryptophan, S-adenosylmethionine (SAMe), St. John's wort, antidepressants, pain killers, over the counter cough and cold medication containing dextromethorphan, anti-nausea medication and anti-migraine medication. Consult a healthcare practitioner if symptoms persist or worsen. Discontinue use and consult a healthcare practitioner if you show signs of weakness, oral ulcers, abdominal pain accompanied by severe muscle pain, or experience skin changes. Some people may experience drowsiness, diarrhea, nausea, vomiting and abdominal pain. Exercise caution if operating heavy machinery, driving a motor vehicle or involved in activities requiring mental alertness. Folic acid supplementation may mask a B12 deficiency; ask your healthcare practitioner if you are taking sufficient B12.