OK, so you have umpteen million pills y'gotta take every day, and many of them look too similar: they're round, white, and roughly the same size. You probably keep your pills organized in a pillcase that has a single small box for each day of the week, day of the month, or 3 or 4 times a day for one week.
You may be taking them under low light conditions, or when you're easily distracted...or maybe your up-close eyesight isn't sharp.
So, what can you do?
Here are two suggestions, one of which I do myself (and it works great).
make a stamp-pad by cutting sponges or folding napkins/handkerchiefs to fit inside an Altoids tin box. Soak the sponges/napkins/handkerchiefs in food coloring (available at any supermarket). Put one set of pills in there, close the lid, and wait a moment so that color soaks into the pills. Also mark the pill bottle with the same color, so you know which color goes with which medicine.
Buy a few food-coloring felt tip marker pens. Here's one company that sells them-- but this company isn't cheap. ( Inkedibles www.inkedibles.com/
)$2 per pen, $5 shipping in the USA.
You can probably get them cheaper on eBay. (ebay search for FOOD COLORING PEN www.ebay.com/sch/i.html?_trksi…
) I see at least one company that sells packs of 10 differently colored food coloring pens for $10.
OR...what I did was, around Halloween/Christmas/Easter, the supermarket sells rectangular cookies with white icing & three foodcolor pens, with a seasonal coloring-book outline on the cookies. After the holiday passes, you can buy these cookie-and-color kits for half-price, gobble the cookie, and have three differently-colored food coloring pens.
Make distinctive marks on BOTH sides of each pill, and draw the same emblem in the same color on the pill bottles. I use a combination of colors and patterns: dots, slashes, Xs, and circles.
Be aware that some colors look the same in low-light conditions. Remember the poem at the end of the Moody Blues song, "Nights in white satin":
"Cold-hearted orb that rules the night / removes the colors from our sight / red is grey, and yellow, white / but WE decide which is right, and which is illusion."
BE CONSISTENT from month to month.
Also, if your vision isn't great or you take these things in the dark, you may want to soak them in different FLAVORS such as a dash of lemon juice (not too much, or the pills will get mushy like wet paper). That way, if you accidentally take the wrong pill you may instantly be aware of the error (before swallowing) by the taste. Maybe you could use those little drop-by-drop dispensers from the supermarket aisle where drink mixes are sold? ( www.google.com/search?site=&tb…
) Or small bottles of vanilla essence, lemon juice, and so on?