What is the best readily available cough medicine?

What helped before: Cough medicines are for decreasing the urge to cough, due to tickling, mucus, or mild irritation in the throat. Coughing is desired and is needed when there is mucus lower in the throat, or coming from the lungs (otherwise, mucus would stay in the lungs and lead to pneumonia). Menthol lozenges +/- anesthetic in the lozenge, can help. Robitussin dm (guaifenesin and dextromethorphan) +/- "cold medicines", can help. Sipping tea helps.

Depends...: Treatment for cough is dependent on the etiology of the cough. If acute bronchitis is present, the treatment is very different than if the cough is due to gerd, for example. So, the best "cough medicine" depends on the underlying diagnosis.