If you are like me (read here: short term memory loss due to children) and you have trouble remembering which kid you gave what medicine to on which day I've got a great trick for you. Parent Hacks comes through once again with the plan. Kristi uses Sharpies (I love Sharpies. They are good for everything) and writes right on the bottle.
She writes letters for each day of the week on the bottle and then marks under the day whenever she gives her son his medicine.
In the comments somebody even suggests using the days of the week stickers from you birth control pills to save time and so you don't have to be as concerned about the ink eventually leaking into the bottle.
This is brilliant. It is so simple, yet it could really help me stop worrying about if I am going to accidentally give my kid an overdose, or if I didn't give him any medicine at all that day.