Getting rid of old medicines is fast becoming a problem, flushing them down the toilet might end up with our sources of drinking-water being contaminated. It was found recently that very low levels of over-the-counter and prescription drugs, including hormones from birth pills, it seems that neither treatment plants nor septic systems have been designed to remove drugs from waste water. What effects, if any, exposure to these low-level mixtures of drugs might have an aquatic life or people still being determined. Although trace amounts of some medication will be excreted through urine and could therefore get into groundwater, minimising potential pollution by not flushing old medication would help.
Here are a couple of rules:
1) 1) When buying non-prescription drugs, buy in smaller amounts so they can get used before the expiration date.
2) 2) Finish all your prescribed medication. A course of tablets is given for your health improvement so take them all.
3) 3) If you do have any unwanted drugs take them back to your local pharmacist who should be able to dispose of them for you.