Manufactured and distributed by Bayer and based on the ostensibly lovable characters by Hanna-Barbera, Flintstones Chewable Vitamins have been a staple of American childhood nutrition since they were first introduced in 1968.
Thanks to the miracle of useless marketing propagation, you can no longer buy plain old Flintstones vitamins, but must choose one of the five different formulations now available: My First Flintstones (for children 2 and 3 years of age), Flintstones plus Extra C, Flintstones plus Iron, Flintstones plus Calcium, and Flintstones Complete (which contains additional vitamin C, iron, and calcium). Bayer apparently discontinued the "Flintstones Original" variety sometime in the year 2000, although it is still available from a few online drugstore websites (the efficacy of such aged vitamins is questionable, though).
Back in the day, Flintstones vitamins came in three flavors (cherry, orange, and grape) and seven shapes (Fred, Wilma, Pebbles, Dino, Barney, Bamm-Bamm, and the Flintmobile, the Flintstones' bipedally powered car). Currently, the available shapes and flavors depend on which variety you buy, but most of the different formulations have added the flavors strawberry, raspberry, and peach-apricot. In 1995, Bayer discontinued the Flintmobile and replaced it with a Betty shaped vitamin. Recently, for some unfathomable reason, they also added a vitamin shaped like The Great Gazoo, a universally reviled alien character that was added to the Flintstones cartoon towards the end of its run when the ratings started to drop.
Although the Flintstones vitamins are much beloved by kids and Gen-Xers alike (due in no small part to the enormously successful advertising campaign conceived in the early 80s: "We are Flintstones Kids, 10 million strong....and growing!"), they can also pose a significant health hazard. The problem inherent with producing a medication (yes, multivitamins qualify as medicine) that appeals to children is that kids hate taking medicine, but there's something they love above all else: candy. Thus, the Flintstones vitamins look like candy, taste like candy, and, until relatively recently, were even marketed directly to children. In adults, a vitamin overdose is generally little cause for concern, but young children are a different matter entirely.
As anecdotal evidence of the potential dangers of chewable vitamins, at one time or another during our childhoods, I and both of my siblings overdosed on Flintstones vitamins. In my case, when I was 4 years old, I snuck out of my bedroom after my parents were asleep, and used a footstool to climb up on the kitchen counter and open the cabinet where the vitamins were stored. I consumed the better part of a bottle of Flintstones vitamins, first biting off all of their heads, and then chowing down on their decapitated bodies. A few hours later, I started to feel sick, and spent the rest of the night puking my guts out. At dawn, my parents discovered me passed out on the bathroom floor and rushed me to the ER. After that, my parents made a point of stocking syrup of ipecac in the house and kept a closer eye on the medicine cabinet, so they were able to induce vomiting shortly after my sister, and later my brother attempted similar feats. No matter where they stored the vitamins, we always managed to find them, and the childproof cap proved to be no deterrent at all.
Of course, if your children aren't little hellions, Flintstones vitamins are absolutely safe, provided you follow the directions on the packaging.
The ingredients in Flintstones Chewable Vitamins vary widely depending on which variety you have purchased. Information specific to each formulation can be found at: http://www.bayercare.com/htm/flinthome.htm.