Clear pill capsules are most commonly made of gelatin, a protein derived from animal collagen. If the capsule is plant-based, it’s typically made from a cellulose derivative called hypromellose (HPMC) or, less commonly, a fermented polysaccharide called pullulan. All three materials can produce transparent shells, though each comes from a very different source.
Gelatin: The Most Common Material
The majority of clear capsules on pharmacy and supplement shelves are gelatin. This protein is extracted from the skin, bones, and connective tissues of animals, usually pigs, cows, or fish. The manufacturing process breaks down collagen through partial hydrolysis, essentially using heat and either an acid or alkaline solution to unravel the protein’s structure into a form that can be molded into thin, flexible shells.
The production involves seven steps: cleaning, pretreatment, extraction, filtration, concentration, sterilization, and drying. Acid extraction is the most widely used method and relies on mild acids like acetic or citric acid. The result is a material that naturally has a light amber to light-yellowish tint when no colorants are added. Manufacturers can add small amounts of colorant (typically 0.5 to 1.0% of the shell’s weight) to change its appearance, but without any additives, gelatin capsules appear mostly clear with that faint yellow tone.
Finished gelatin capsules need to maintain a moisture content of about 13 to 16% to stay structurally sound. Too dry and they become brittle and crack; too moist and they soften or stick together. This is why storage conditions matter for any medication or supplement in a gelatin capsule.
HPMC: The Plant-Based Alternative
Hypromellose capsules, often labeled “vegetarian capsules” or “veggie caps,” are made from cellulose, the structural fiber in plant cell walls. Cellulose is a natural polymer built from repeating units of glucose. To turn it into a capsule-friendly material, manufacturers treat it with an alkaline base and then chemically modify it by attaching methyl and hydroxypropyl groups to the cellulose chain. The result is a semi-synthetic material that dissolves predictably in your stomach and forms a clear, flexible shell.
HPMC capsules look very similar to gelatin capsules and are functionally interchangeable for most medications and supplements. In studies comparing the two, both types disintegrate in the stomach within a similar timeframe. Gelatin capsules broke down in an average of about 7 minutes, while HPMC capsules averaged around 9 minutes. The difference was not statistically significant, meaning your body processes them at roughly the same speed.
Pullulan: A Fermentation-Based Option
Pullulan capsules are the newest and least common of the three. Pullulan is a polysaccharide (a type of complex sugar) produced by fermenting starch with a fungus called Aureobasidium pullulans, sometimes referred to as “black yeast” because it produces a dark pigment called melanin. The fungus secretes pullulan as an amorphous slime on its cell surface during fermentation, and this material is then collected and purified.
Pullulan capsules tend to have excellent clarity and a very low oxygen permeability, which makes them appealing for supplements that are sensitive to oxidation, like certain oils or probiotics. They’re plant-compatible and suitable for vegan labeling.
What Makes a Capsule Clear vs. Opaque
The difference between a clear capsule and an opaque one comes down to whether an opacifying agent has been added to the shell formula. Titanium dioxide has historically been the standard opacifier, creating the solid white or colored appearance you see in many prescription medications. When that ingredient is left out and no heavy pigments are added, the capsule shell remains transparent or semi-transparent. A “clear” capsule is simply one made without these opacifiers, allowing you to see the powder, liquid, or beads inside.
Dietary and Religious Considerations
Because standard gelatin capsules come from pigs or cows, they raise issues for people following vegetarian, vegan, kosher, or halal diets. Porcine (pig-derived) gelatin is not halal or kosher. Bovine (cow-derived) gelatin can qualify, but only if the animal was slaughtered according to the relevant religious guidelines and the entire production chain is certified. Halal pharmaceutical standards require that all ingredients be free from pork, blood, and parts of carnivorous animals, and that halal production lines be physically separated from non-halal ones to prevent cross-contamination.
HPMC and pullulan capsules sidestep these concerns entirely. They contain no animal-derived ingredients and are suitable for vegan, vegetarian, halal, and kosher diets without requiring special certification of animal sourcing. If this matters to you, check the supplement label for terms like “vegetable capsule,” “HPMC,” “hypromellose,” or “pullulan.” If the label simply says “gelatin,” it’s animal-derived.
How to Tell What Your Capsule Is Made Of
The capsule material is listed in the “other ingredients” or “inactive ingredients” section of the label, not in the main supplement or drug facts panel. Look for “gelatin” (animal-based), “hypromellose” or “HPMC” (plant cellulose), or “pullulan” (fermented polysaccharide). Some labels use the phrase “vegetable capsule” as shorthand for HPMC. If you’re buying a prescription medication and the packaging doesn’t specify, your pharmacist can look up the inactive ingredients for your exact product.