I have a cough what is the best medicine i will take?

Extra fluid: Drink extra water, this will loosen the secretions and allow you to cough up the material easier.

Few. Humidification?: Cough=a backup protective mechanism after the mucocilliary elevator has not worked well enough. Study: http://goo.gl/IXDw19. Suppressing cough further ↓es clearing lung air passages. In clinical trials, cough meds have little efficacy, despite ads. More important issue=addressing what is driving the air passage irritation: inhaled particles, asthma, virus, sometimes bacteria, CHF, rarely cancer.