What would be safer to take guaifenesin of carbocesteine for common cold and cough?

Either: Taken as directed, both are safe and neither will affect the course of illness. Have a healthy diet, exercise 30 minutes/day, drink plenty of water daily so your urine is mostly colorless, have safe sex, no tobacco alcohol weed or street drugs. For nutrition: http://www.choosemyplate.gov/. Get HPV and Covid vaccines. Wish you good health!