The 2006 movie “Fast Food Nation” is a fictionalized account of what it takes to bring hamburger from farm to drive-thru — and the hidden “ingredients” that horrible slaughterhouse practices add to the meat.

Now, a study tells the real story about ingredients that often are hidden in your over-the-counter and prescription medications as they go from lab to pharmacy or retail shelf.

It turns out inactive ingredients such as gluten, peanut oil, lactose, certain sugars, and food dyes, which are used to help bind, stabilize, or boost absorption of medications, are often triggers for gastrointestinal problems such as irritable bowel syndrome, as well as allergenic or sensitivity reactions.

The study, which was published in Science Translational Medicine, looked at ingredients in prescription and nonprescription medications and found that in most instances, inactive ingredients account for more than 50 percent of a medication — and sometimes up to 99 percent.

Currently, the Food and Drug Administration requires companies to include an additive warning only for peanut oil, and says the amount of other inactive ingredients is next to none.

But if you're someone with a food allergy or sensitivity, a little can still be a lot.

So if you're having a nontypical reaction to a medication, ask a pharmacist or doctor about the inactive ingredients in all versions of the drug, including various generics. Many may have different inactive ingredients.

If all versions contain a problematic inactive ingredient, consider ordering a custom formulation from a compounding pharmacy. If it allows you to take necessary medication, it could be an important option.