not for kids it isn't, my son has food and allergies to amoxicillin, he was given bendryll because the penecillin brought him out in a rash with flu symptoms . The doctor told me when he prescribed it to ONLY use what was needed and warned of all the side effects such as headaches, sickness, upset tummy and drowsiness.
as for cough medicine that's even worse...
Treating children
The Medicines and Healthcare products Regulatory Agency (MHRA) has recommended that over-the-counter cough and cold medicines shouldn't be given to children under the age of six.
The MHRA is the government body responsible for ensuring that medicines are safe and effective.
The agency has made this recommendation because it feels there's a potential risk of these medicines causing unpleasant side effects, such as allergic reactions, sleep problems or hallucinations (seeing and hearing things that aren't real). These would outweigh any benefit provided by the medicines.
Instead, give your child a warm drink of lemon and honey or a simple cough syrup that contains glycerol or honey.
However, honey shouldn't be given to babies under the age of one, due to the risk of infant botulism.
For more information, see News: child cold medicines Q&A.