You asked

Children’s cough and cold medicine: what is appropriate at what age?

Ideally, when your child gets sick, you should take him or her to the doctor, for proper diagnosis and treatment. However, sometimes it is okay to use over the counter medication to treat minor coughs, colds and fevers, or as a temporary measure, until you can seek proper medical attention.
It’s worth remembering that over the counter medicines don’t cure coughs or colds – they simply lessen the symptoms. It’s your child’s own immune system that fights off the viruses that cause coughs, colds and fevers. You also need to remember that you should only ever give your child age appropriate medications, in the correct doses, and that adult medications, including aspirin, are never safe for children!
Paracetamol pain and fever relievers are safe to use with children aged from shortly after birth to five months, although with children under three months, this should only be done with your doctor’s advice. Don’t use ibuprofen for children under five months.
Children between five months and six years can safely take both paracetamol and ibuprofen, although you should always follow the dosing instructions carefully.
Over the counter expectorants, decongestants, antihistamines and cough suppressants should not be used for children under the age of four, but most are okay for children aged four to six years. Always read labels carefully.
If in doubt about any medication, make sure that you check with your doctor or pharmacist. In most cases, however, it’s a good idea not to try alternative or home remedies on children who are babies or toddlers.

More questions

Your child's baby teeth are still very important as they need them to be able to chew food and speak clearly.
A cold bath can actually do more harm than good to a feverish child.
Many children have a mild reaction to the MMR vaccine – it’s not usually full-blown measles though, and it’s usually not serious. There are a few things to watch out for though...
Injections are necessary - the thing is to just have them and then get on with it. If needs be, have your child’s favourite toy or something else that will distract him while he has his shot.
Antibiotics do not kill viruses, such as the common cold, and by over using antibiotics, particularly when they aren’t necessary, you are weakening your child's future defences! 
In general, chewable medicines are only designed for children two years and older, who are adept at eating solid foods.
Giving any child aspirin could contribute to them getting a serious illness known as Reye’s Syndrome.
As a parent you should understand the risks associated with various different types of medication
Both ibuprofen and paracetamol are effective pain and fever treatment options for babies and children.
Choosing between a vaporiser and a humidifier is a personal choice but both help to make children feel better