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Glossary

What is a capsule pill?

Written by the Full Measure editorial team, which sells supplements. Approved for publication by the Full Measure owners. Updated .

Drafted with AI assistance from the sources listed below. How we write these

Quick answer

A capsule is a dose form in which the ingredients sit inside a soluble shell that you swallow whole. Shells can be hard or soft and are usually made of gelatin or of a plant-based polymer such as hypromellose. Hard capsules are two pieces that fit together, most often around a powder.1,2,3

Key facts

  • FDA's drug rules describe a finished dosage form, such as a tablet or capsule, as usually holding inactive ingredients alongside the active one.4
  • Capsules can hold nonaqueous liquids and semisolids as well as powders, an advantage over tablets noted in a 2017 review.2
  • Capsule shells can be made to release their contents at a chosen place in the gut.2
  • NIH lists capsules with tablets, gummies and powders as common supplement forms.5

What the shell is made of

  • Gelatin: made from collagen in animal skin, connective tissue or bone, and long used to make capsules.6
  • Hypromellose (HPMC): a cellulose derived from plant fiber, developed to replace animal gelatin in two-piece capsules.3,7
  • Starch and other non-gelatin polymers: used for some hard and soft shells, together with water and sometimes a plasticizer.2

Hard capsules, softgels and special release

A hard capsule is two pieces that close over a dry fill. A softgel is a single sealed shell, thicker and more flexible, around a liquid. FDA's list of dosage forms counts both as capsules and adds variants such as delayed release, extended release and liquid filled capsules.3,8,9

A delayed release capsule holds its contents back until after the stomach, while an extended release capsule lets them out slowly. Plain capsules have neither feature and open soon after you swallow them.10,11

What a capsule label lists

The shell is part of what you swallow, so it belongs in the ingredient list. FDA requires that list to include everything that is not a dietary ingredient, such as excipients, fillers, colors and binders, and the label groups them under Other ingredients when the sources are named in the Supplement Facts panel.12,13

Other ingredients on capsule labels can include rice flour, microcrystalline cellulose, magnesium stearate or silicon dioxide. FDA's food additive rules describe the jobs such ingredients do: fillers and binders, lubricants that keep powder from sticking to equipment, and free flow agents.14,15

Questions people ask

Are capsules better than tablets?

Neither is better across the board. Capsules can carry liquids and semisolids as well as powders, while tablets are pressed from powder and often rely on binders to hold together. The ingredient, its form and the dose matter more than the shell.2,16,17

What are capsules made of for supplements?

Most shells are gelatin, made from animal collagen, or hypromellose, made from plant cellulose. Starch and other polymers are also used. The other ingredients list shows which one a product uses.2,3,6,12

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Sources

  1. NCI Thesaurus, NCI Enterprise Vocabulary Services, National Institutes of Health. Capsule Dosage Form, code C25158. Opened 2026-10-07.
  2. Gullapalli RP, Mazzitelli CL. Gelatin and Non-Gelatin Capsule Dosage Forms. J Pharm Sci. 2017;106(6):1453-1465. Opened 2026-10-07.
  3. Al-Tabakha MM. HPMC capsules: current status and future prospects. J Pharm Pharm Sci. 2010;13(3):428-442. Opened 2026-10-07.
  4. Code of Federal Regulations, Title 21, Section 210.3: Definitions (current good manufacturing practice for drugs). eCFR, current as of October 2026. Opened 2026-10-07.
  5. Office of Dietary Supplements, National Institutes of Health. Dietary Supplements: What You Need to Know, Fact Sheet for Consumers. Updated January 4, 2023. Opened 2026-10-07.
  6. Medical Subject Headings, U.S. National Library of Medicine. Gelatin, descriptor D005780. Opened 2026-10-07.
  7. EFSA Panel on Food Additives and Nutrient Sources added to Food. Re-evaluation of celluloses E 460(i), E 460(ii), E 461, E 462, E 463, E 464, E 465, E 466, E 468 and E 469 as food additives. EFSA J. 2018;16(1):e05047. Opened 2026-10-07.
  8. NCI Thesaurus, NCI Enterprise Vocabulary Services, National Institutes of Health. Liquid Filled Capsule Dosage Form, code C42954. Opened 2026-10-07.
  9. U.S. Food and Drug Administration. Structured Product Labeling Resources: Dosage Forms. Content current as of February 3, 2022. Opened 2026-10-07.
  10. NCI Thesaurus, NCI Enterprise Vocabulary Services, National Institutes of Health. Delayed Release Capsule Dosage Form, code C42902. Opened 2026-10-07.
  11. NCI Thesaurus, NCI Enterprise Vocabulary Services, National Institutes of Health. Extended Release Capsule Dosage Form, code C42916. Opened 2026-10-07.
  12. Code of Federal Regulations, Title 21, Section 101.4: Food; designation of ingredients. eCFR, current as of October 2026. Opened 2026-10-07.
  13. U.S. Food and Drug Administration. Dietary Supplement Labeling Guide: Chapter V. Ingredient Labeling. April 2005. Opened 2026-10-07.
  14. Office of Dietary Supplements, National Institutes of Health. Dietary Supplement Label Database: search for rice flour, and a review of 50 matching labels, October 7, 2026. Opened 2026-10-07.
  15. Code of Federal Regulations, Title 21, Section 170.3: Definitions (food additives). eCFR, current as of October 2026. Opened 2026-10-07.
  16. NCI Thesaurus, NCI Enterprise Vocabulary Services, National Institutes of Health. Tablet Dosage Form, code C42998. Opened 2026-10-07.
  17. Thoorens G, Krier F, Leclercq B, Carlin B, Evrard B. Microcrystalline cellulose, a direct compression binder in a quality by design environment: a review. Int J Pharm. 2014;473(1-2):64-72. Opened 2026-10-07.

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