How can I get my 18 month old to take medicine?

Is it liquid or what?  Pills I crushed into sorbet.  For liquid, if necessary, I would hold open their mouth and pour it down the far back of their throat, and hold their mouth closed for a few seconds to make sure they swallow.  

If her fever isn't high, I would forgo the meds. They actually help fight whatever is going on in her body and treating the fever instead of the symptoms can counteract the bodies natural immunity responses. 
I would try a cool cloth on the back of her neck, maybe a lukewarm bath with some toys.
Good luck, I hope she feels better soon. 

She's only 18 months, liquids

Quoting mmccrea:

Is it liquid or what?  Pills I crushed into sorbet.  For liquid, if necessary, I would hold open their mouth and pour it down the far back of their throat, and hold their mouth closed for a few seconds to make sure they swallow.  

 I'm assuming you've tried a dropper, cup and spoon? Have you tried mixing it with some yogurt or icecream? (assuming she likes those :) What's her temp? 

Try giving her a cup of pudding or something similar and hiding it in there.

Take a dropper, hold open her mouth put it as far bacl as you can without choking her and squirt it gently then hold gently blow in her face which will make a reaction to swollow. My oldest dd had super high temps and nacl to back ear infections from 16mths till past 2. I had to do it almost everytime to get her to take meds. It doesn't sound nice and it seems harsh but it works. And it hurts you more than her.