Looking for suggestions for an icon on our website to indicate correct dosage and usage of medication.
What about an Erlenmeyer flask?
You could just have a count of pills.
I believe the pharmaceutical industry has standard pictograms for such things. You can download some of those pictograms here:
You may also want to take a look at this example:
Are you looking for a general icon to communicate the concept of dosage (i.e. "Dosage Info Here") information, or specific iconography to communicate dosage instructions (i.e. "Take 2 pills every 4 hours")?
I've worked on a very extensive medication dosing icon project. I did about 300 icons as broad exploration and then several of those were tested with consumers over a period of several months and many rounds of iteration.
If you are looking for a general icon, you can't go wrong with something like pills falling into a hand, or a bottle with some pills next to it.
For more specific iconographic instruction, the key takeaway is to be as literal as possible. If the instruction is to take 2 pills, the icon must incorporate 2 pills. You cannot use a clock as an abstract representation of time — if the hands on the clock read 3:45, someone will believe they are being instructed to take pills at 3:45. What works best is more illustrative instruction. If I am being told to take 1 pill every 12 hours, I should see a single pill maybe falling into a hand with text underneath that says "every 12 hrs".
Having worked in this space, I can tell you I really wanted iconography to work, but there were few cases where the icons helped compliance without creating more problems. The key to better compliance with medical information is going to depend more on typographic hierarchy and clear organization and language.
The noun project has a bunch of good icons for health & wellness at http://thenounproject.com/category/healthcare-wellness/
try icon finder, it may help http://www.iconfinder.com/search/?q=medical