I am a mum of three.
If the DCs just have a bit of a temperature, I leave nature to take its course, as it's probably a natural process. I do make sure they're not overdressed and that their bedding is light, however. I make sure they have lots of fluids, and sit in their room a bit to keep them company.
If their temperatures are a bit higher, and they are grumpy and obviously suffering a bit I do all that plus give them some Calpol or Ibuprofen, the lowest dose for their age.
If they are really struggling a bit, and their temperature is around the 40 mark, I also measure their temperatures with a thermometer and keep a record of it, put them in a nappy or pair of pants, with a sheet over them, and alternate Calpol and Ibuprofen at the highest dose on the label on the bottle, in a very scientific and regimented manner with a record being kept. I also check for meningitis etc. I would consider putting them in a lukewarm bath or shower and letting them have a play, partly to cool them down a bit, partly to cheer them up, and partly to see what their reaction is to the changed environment.
If they are ill for a longer period of time (eg 6 hours during the day) with no occasional periods of respite or relative cheerfulness at all, or not taking fluids, I would always call the GP or NHS Direct for advice.
If they are over about 6 months, and bunged up as well as having a temperature, and look like they could do with a good night's sleep to fight to bug off, I would dose them with Medised instead of using Calpol, watching the overall dose of Paracetemol they got in any 24 hour period so there was no liver damage. I would tell my GP I had done this.
BTW I have never given mine cough mixtures or things like that - they just get honey in hot water, or Bryonia homeopathic stuff if we happen to have some in the house, because most coughs go of their own accord, and if they don't, the GP needs to see the child.