Excipient Meaning: What Excipients Do

Quick answer

An excipient is an ingredient added to a supplement or medicine for a reason other than its intended effect: to fill, bind, coat, color or flavor the product, or to help powders flow during manufacturing. On a supplement label, excipients appear in the ingredient list, often headed Other ingredients.^1,2,3,4

Key facts

FDA requires ingredients that are not dietary ingredients, such as excipients, fillers, artificial colors, artificial sweeteners, flavors and binders, to be included in the ingredient list.²
When the label names sources inside the Supplement Facts panel, the remaining ingredients are listed under the words Other ingredients.^2,3
In FDA's drug manufacturing rules, an inactive ingredient is any component other than an active ingredient.⁵
The National Library of Medicine describes excipients as usually inert substances that give a dose form a suitable consistency, such as binders and diluents.⁶
Ingredients in the list appear in descending order of weight.³

Common excipients and their jobs

Excipients you may see on supplement labels^{4,6,7,8,9,10,11}
Job	What it does	Examples
Filler or diluent	Adds bulk so a dose can be handled and measured	Rice flour, microcrystalline cellulose
Binder	Holds a pressed tablet together	Microcrystalline cellulose
Lubricant	Keeps powder from sticking to equipment	Magnesium stearate
Anticaking or flow agent	Keeps powders from clumping	Silicon dioxide
Shell or coating	Holds or covers the dose	Gelatin, hypromellose

Why they are there

Excipients make a product possible to manufacture and to take. The NCI Thesaurus, a terminology published by NIH, lists their purposes: easier manufacture and dosing, consistent release, stability and identification. They are not meant to change what the active ingredient does.¹

Botanical extracts often carry excipients too. Carriers are added to native extracts to make them easier to handle and to adjust the level of key compounds, which is one reason an extract's strength is hard to judge from its name alone.¹²

Each excipient has its own status

There is no single rule for all excipients. FDA affirms magnesium stearate as GRAS for use as a lubricant, permits silicon dioxide as a food additive with a 2% limit for anticaking use, and permits hypromellose as a film former. Some people avoid particular excipients, such as gelatin from animals, for dietary reasons, which is why the full ingredient list matters.^2,8,9,13,14

Questions people ask

Are excipients the same as fillers?

Fillers are one kind of excipient. The word also covers binders, lubricants, flow agents, shells, coatings, colors, flavors and sweeteners.^2,4,6

Do excipients count toward the dose?

No. The Supplement Facts panel lists dietary ingredients and their amounts. Excipients are listed by name only in the ingredient list, in order of weight.^3,15

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Sources

This page is information, not medical advice. Talk to your doctor or pharmacist about your own situation.