Beechams All In One Tablets is a treatment that is intended to be used by anyone who is suffering from the effects of a cold or the flu, including a chesty cough. Other symptoms that these tablets can treat include headaches, shivers, aches and pains, a blocked nose, and a sore throat. The tablets contain three active ingredients which work to provide relief. These ingredients are:

Paracetamol
Phenylephrine hydrochloride
Guaifenesin
Paracetamol is a painkiller that will also help to reduce a fever. Phenylephrine hydrochloride is a decongestant that will unblock to nose and sinuses. Guaifenesin is an expectorant which will loosen the phlegm that is causing a chesty cough.