How Long Does It Take for Calpol (Paracetemol) to Effect?

(For anyone stateside who doesn't know: Paracetamol is Tylenol's brand name everywhere else in the world but here. Nurofen is a UK brand of Ibuprofen)

20 minutes. For either. Or both.

It's called a "stubborn" fever if it's high and only going down a smidge on antipyretics.

Paracetamol & Nurofen (tylenol & ibuprofen) can be taken at the same time, full dose of each (they have different modes of action). For stubborn fevers, we always double up with both. For high but "easy" fevers we may alternate, but with stubborn ones, hit it with both. If you're giving both at the same time and his fever is still 103 / 39.4 ... after about 30 minutes - 60 minutes you need to go back in and be seen again. If it's CLIMBING with both in his system, don't wait. Head back in.

A LUKEWARM (NOT COOL!!!!) bath can also help lower a fever. Test the water just like a baby bottle on the inside of your wrist. It should be that warm. A cool or cold bath with a fever can (and often does) cause shock and seizures. LUKEWARM. Lukewarm will feel icy to him (warm to you), but it won't shock his system and will bring his temperature down a smidge. Again, if it's not.... he needs to be treated at the hospital.

So sorry! It's so hard when these little ones are taken sick!

You're giving him opium-that's why he's tired.

There is no opiates in paracetamol, or nurofen Robin. Unless you use nurofen plus, which has a small amount of codeine in it. Paracetamol in the UK, is the same as acetominophen.

Don't forget V. that fever is our bodies way of raising our temperature to a level inhospitable to viruses and bacteria, so fever is a good thing. But you are right to try and get it down from 104!
He probably has streptococcus pyogenes (UK tonsilitis, USA, strep throat) makes you very sick, and not want to do much.

Paracetamol = Tylenol = acetominofen which for me and my kids does NOTHING. Doctors recommend it first since it tends to cause less stomach irritation, but for us it has no fever reducing effects. For that reason we take ibuprofin = Advil or Motrin. I started using it for the kids when they were infants (it comes in dropper bottles for babies) since the Tylenol infant drops had no effect.
So perhaps the medicine is not really helping his fever or pain and therefor he is not acting like he feels better.
By the way - my doctor always says that she worries more about a child not "acting himself" than the actual number of degrees of fever. A child with a mild fever acting lethargic is far more worrying than a child with a higher fever playing like nothing is wrong.
I would run this by your doctor again.

Thank you to Riley for your explanation of Paracetamol! Anyway, it is so hard to be worrying about your baby. If he is really lethargic and you don't see temperature change in or climbing please call doctor or go to emergency room soon. Only you know what your son is usually like, but those are high temps. For now, besides writing us, call your local pharmacist, or clinics or even ask for a nurse in the pediatrics department of your local hospital. They are all sources of information who can lend what they know about results of the tylenol or ibuprofen and I used to find them really helpful when I couldn't reach doctor right away. Good luck! HUGS