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What are gelatin capsules made of?
Beyond Biopharma | Pharmaceutical Gelatin FAQ
Short answer: A conventional hard capsule shell is made essentially of gelatin and water, with optional colourants, opacifiers or approved processing aids, while a softgel shell also contains a plasticiser such as glycerol or sorbitol, which keeps the one-piece shell soft and flexible. Every ingredient is chosen for excipient use, and the shell recipe is balanced so the capsule opens, dissolves or releases its contents reliably after swallowing.
The two capsule families
Gelatin capsules fall into two families with different construction and therefore slightly different compositions. A hard (two-piece) capsule is a dry shell with a body and a cap that lock together and is normally filled with powder, granules, pellets or small tablets. A softgel is a one-piece, sealed shell that is formed and filled in a single operation and is normally used for liquids, suspensions and semi-solids. The difference in how they are made drives the difference in what goes into the shell.
Hard capsule shells: gelatin and water
The heart of a hard shell formula is pharmaceutical-grade gelatin, dissolved in purified water to make the dipping solution, with colourants or opacifiers added when a coloured or opaque shell is wanted. The finished shell still holds a small amount of water, commonly in the region of 12-16 % as a typical reference, which gives the shell its slight flexibility; too little water makes it brittle and too much makes it soften or distort. Very small amounts of approved processing aids may be used where needed to help the shell release from the pins, and all additives are selected from excipients accepted for the purpose.
Softgel shells: gelatin plus a plasticiser
A softgel shell must stay soft and elastic for years on the shelf, which plain gelatin and water cannot guarantee because water slowly escapes from the shell. The shell formula therefore adds a plasticiser, most commonly glycerol or sorbitol, which holds flexibility inside the shell as water is lost. The ratio of plasticiser to gelatin is one of the main levers in softgel formulation: more plasticiser gives a softer shell, less gives a firmer one. Water, gelatin and plasticiser together make the warm liquid that is cast into ribbons and formed around the fill.
What is in a shell, side by side
| Component | Hard capsule shell | Softgel shell |
|---|---|---|
| Gelatin | Yes, the main structural material | Yes, the main structural material |
| Water | Yes, as process solvent and residual moisture | Yes, as process solvent and plasticising moisture |
| Plasticiser (glycerol or sorbitol) | Normally none, or only a minimal level | Yes, essential for shell flexibility |
| Colourants and opacifiers | Optional, for colour or light protection | Optional, for colour or light protection |
Where the gelatin itself comes from
The gelatin used in both capsule types is a protein obtained by partial hydrolysis of collagen from animal skin and bone. It is usually sold as Type A, made by acid processing and typically from porcine skin, or Type B, made by alkaline processing and typically from bovine sources. Both types can meet pharmacopoeia standards and are used in capsules; the choice depends on the shell maker, the market and the customer requirements, including religious or dietary certification where relevant.
Why the water balance matters so much
Water is easy to overlook because it is not listed as an ingredient, but it is functionally critical in every gelatin shell. It acts as a plasticiser in its own right, it determines whether a shell is flexible or brittle, and it is the reason capsules are packed and stored under controlled conditions. Shell makers and fillers manage moisture carefully during manufacture and storage, and the finished product is expected to remain within its moisture specification through its shelf life.
Related reading
For the safety context, see are gelatin capsules safe and which Bloom strength suits hard capsules versus softgels.
