When you buy an over-the-counter (OTC) medication, you probably have noticed that there are two sections of ingredients listed on the package label: the active and the inactive. The active ingredient, no surprise, is what’s responsible (or thought to be responsible) for the drug’s therapeutic effect. All the rest are considered inactive. (Such ingredients are technically called excipients.)
Oral prescription medications are not required to list their inactive ingredients, though most manufacturers voluntarily do so—but on the package insert, which is not always included when the medication is dispensed unless you ask for it. Non-oral prescription drugs, such as injectables and topicals, must, however, have labeling of inactive ingredients.
What they are, why they’re there
Inactive ingredients—which include aspartame, lactose, sucrose, starches, stearic acid, talc, benzyl alcohol, potassium benzoate, propylene glycol, titanium dioxide, and magnesium stearate, among many others—“are not intended or expected to have direct biological or therapeutic effect,” according to a paper in Science Translational Medicine. Rather, they are there to help ensure that the medication will work as intended and provide other important properties.
That includes making sure the active ingredient is delivered to the targeted part of the body, enabling the drug to withstand acids in the stomach or dissolve slowly as the drug transits the gastrointestinal tract, and improving the ability of the drug to break into small particles so the active ingredient can be adequately absorbed.
Inactive ingredients also act as binders to hold the pills together (lactose, for example), extend the drug’s shelf life (they are used as preservatives), give drugs their color, and mask bitter tastes. In some cases, they serve to boost an active ingredient’s effects—though as an unwanted effect, some may reduce the active ingredient’s bioavailability (the bioavailability of a drug’s ingredient refers to its ability to be absorbed and thereby exert an effect in the body).
Inactive ingredients can come from natural or synthetic sources, as well as from animals or plants. All in all, they make up more than two-thirds of the total mass of oral medications, with each tablet or capsule having an average of nine inactive ingredients.
Regarding safety, drug manufacturers must submit an application to the FDA for approval of inactive ingredients or can assume safety at a certain dosage based on prior approval in a similar type of product. The FDA also has processes in place to monitor drugs made overseas for safety, though how reliably they are carried out is debatable.
Buyer beware
Inactive ingredients aren’t always quite so “inactive,” however—not when it comes to people with food allergies, intolerances, or sensitivities. For example, for people with lactose intolerance, lactose in medication could cause abdominal pain, gas, and other gastrointestinal problems if enough is consumed. One lactose-containing pill is not likely to have a perceptible effect, but taking multiple tablets or several medications containing lactose might set off symptoms in some people. Sodium caseinate or casein, derived from milk, could be a problem for people with true milk allergies; gluten from wheat starches could trigger an immune system reaction and gut inflammation in those with celiac disease (though the FDA maintains that gluten is rarely found in oral medications). And consuming aspartame, casein, or gluten can cause serious health problems in people who have the genetic condition phenylketonuria (PKU).
Other potential allergenic ingredients include dyes and peanut oil. Manufacturers are not required to list allergens per se (such as “gluten”) but should have accurate label information regarding the source of the allergen (“wheat starch,” which may contain residual gluten after processing).
If you seek to avoid animal foods or foods made with animal byproducts, be aware that animal-based inactive ingredients such as gelatin, lactose, beeswax, and lanolin may be present in your meds. Did you know, for instance, that Pepto Bismol LiquiCaps contain gelatin, as do many capsule shells? Gelatin is usually sourced from cows or pigs.
How likely is it that your medication contains a potential allergen or otherwise problematic inactive ingredient? Very. The Science Translational Medicine study noted above found that 93 percent of more than 40,000 oral drugs examined contained at least one inactive ingredient—such as peanut oil, dyes, various sugar compounds, or wheat starch—that could cause an allergic or other type of reaction. More than half contained FODMAPs (an acronym for “fermentable oligosaccharides, disaccharides, monosaccharides, and polyols”), which can set off symptoms in people with irritable bowel syndrome (IBS). In addition, 45 percent of pills (tablets or capsules) contained lactose in quantities that could provoke problems for some people with lactose intolerance.
BOTTOM LINE: If you have any dietary concerns, including allergies, intolerances, or sensitivities—or if your goal is to avoid animal products—check the packages or inserts of OTC medications and talk with your pharmacist before filling a prescription. The pharmacist should be able to enter your allergy and other information into a database for future reference. You can also consult the comprehensive government website DailyMed to see what inactive ingredients are in a medication (after searching for and clicking on your medication, scroll down to “Ingredients and Appearance”); the database has information on more than 140,000 drug labels. A search for a rosuvastatin/ezetimibe formulation, for example, revealed that it contains 16 inactive ingredients, including cornstarch, silicon dioxide, sodium lauryl sulfate, magnesium stearate, mannitol, and titanium dioxide.
Keep in mind also that drug manufacturers may change the formulation of inactive ingredients in medications over time, and generic brands of the same drug can have different inactive ingredients. So if you are concerned about the ingredients, you might want to check the labels or ask the pharmacist each time you buy an OTC medication or fill a prescription, especially if you are switched to a different generic brand.
