My son has the same problem. We have tried hiding it in Juicy juice and now he can taste the difference. Telling him that it because he is sick the Juicy juice will taste different, doesn't work.
Do a search on natural cough remedies.
We like honey. That naturally coats the throat. You could see if he/she would take a sip on a spoon.
What we are doing now: If our son looks like he is a little under the weather, I make a "Sweet Echenacia(spelling?)" Tea. I use what is recommended on the bottle in some warm water (NOT HOT) and add some honey. If he is running a fever, I may simmer some sliced ginger root and Red raspberry Green leaves and peppermint or spearmint leaves in a pot. Once my tea has simmered I store the bulk of it in the Refrig. Then as I think he/myself needs a cup of tea I only put about a 1/4 a cup of my mixture in a coffee cup and I'll mix that with the recommended dosage on the "Sweet Echenacia" (For my self, I use "Golden Seal Echenacia")add warm water to fill up the cup and add honey if it is not sweet enough. For us, that seems to help ward off cold symptoms.
"Sweet Echenacia" comes in a little bottle with an eye dropper, follow the guide lines. YOu can buy this at most health food stores. I have never seen it in a standard grocery store.
Ginger is a natural fever reducer. Since I personally am so sensitive to over the counter meds I started researching natural remedies and the above is what I have discovered in the process. This has really helped my son and myself on many occasions. And my son WILL DRINK IT.
I usually say: "Oh you don't feel so good?" He'll reply "Yeah", I'll ask if he would try some of mommies tea and he usually agrees.
I have also used Vicks, but I have put it on him after he falls asleep. I also like Tiger Balm. Usually available in Health food stores. I think it smells better than vicks and you don't need to use a lot. A small dab goes a long way.
I hope this helps.
I recommend doing internet search on "Natural Cough Remedies", "Natural Fever Reducers", "Tiger Balm"
Even put questions in the search field: What is a Natural .... ?
Never let it get out of hand.
Be sure to talk to your Dr.
This is just what we do.