Empty hard gelatin capsules are one of the most versatile dosage forms in medicine and nutrition. The same simple two-piece shell carries prescription drugs, vitamins, herbal powders, probiotics and clinical-trial doses. This guide explains what empty hard gelatin capsules are used for, what you can put in them, and what you should not.
The short answer
Empty hard gelatin capsules are used to deliver an exact dose of a dry ingredient in an easy-to-swallow, taste-masking shell. The main uses are pharmaceutical medicines, nutraceutical and vitamin supplements, Ayurvedic and herbal products, probiotics, veterinary products, clinical trials and pharmacy compounding. They can be filled with powders, granules, pellets and mini-tablets.
What is an empty hard gelatin capsule?
An empty hard gelatin capsule is a two-piece shell made of pharmaceutical-grade gelatin: a longer body that is filled, and a shorter cap that locks over it. The shell holds its contents securely, masks taste and odour, and dissolves at body temperature in the stomach to release the dose. Capsules come in eight standard sizes, from 000 (largest) to 5 (smallest), so the same format works for doses from a few milligrams to over a gram. See our empty capsule size chart.
The main uses of empty hard gelatin capsules
Pharmaceutical medicines
Prescription and over-the-counter medicines are filled into hard gelatin capsules because the format needs few excipients and no compression, keeping the formulation simple and the dose accurate.
Nutraceuticals and vitamins
Multivitamins, minerals, sports and wellness supplements use capsules for convenient dosing and a clean, premium appearance.
Ayurvedic and herbal products
Herbal powders and extracts often taste bitter or smell strong. A capsule hides both and turns a loose powder into a measured daily dose.
Probiotics and enzymes
Dry probiotic and enzyme blends are filled into capsules to give a convenient, accurately measured dose.
Clinical trials and R&D
Capsules are ideal for small batches and dose-finding studies, and for blinding: a tablet can be placed inside an opaque capsule so patients cannot tell treatments apart.
Veterinary and compounding
Veterinary products and pharmacy compounding use capsules to make custom doses quickly, in any strength, without tablet presses.
What can you fill into a hard gelatin capsule?
| Fill type | Typical use | Notes |
|---|---|---|
| Powders | Most medicines and supplements | The most common fill; a free-flowing blend fills most evenly |
| Granules | Medicines needing better flow or density | Granulating a powder lets more fit into a smaller size |
| Pellets and beads | Modified-release and taste-masked products | Coated pellets can release the drug over time |
| Mini-tablets | Combination and paediatric products | Several small tablets can be combined in one capsule |
| Tablet inside a capsule | Clinical-trial blinding | An opaque capsule hides the identity of the tablet |
What should not go into a gelatin capsule?
Hard gelatin shells are designed for dry fills. Avoid water-based liquids, which soften and dissolve the shell, and fills that are strongly hygroscopic, which can draw moisture out of the gelatin and make it brittle. Very acidic or alkaline fills, and ingredients that react with gelatin, should be tested for compatibility first. If in doubt, run a stability test on filled capsules before you scale up.
Why manufacturers choose hard gelatin capsules
- Fast release: the shell dissolves quickly at body temperature. Read more about capsule dissolution and disintegration.
- Easy to swallow and masks bitter tastes and strong odours.
- Simple to make: no compression, few excipients, and fills run on manual, semi-automatic and fully automatic machines.
- Brandable: any cap and body colour, plus printing of a name, logo or strength.
- Economical: gelatin is a well-established, widely available raw material.
For a fuller comparison, read why choose hard gelatin capsules and capsules vs tablets.
Frequently asked questions
What are empty gelatin capsules used for?
To hold and deliver an exact dose of a dry ingredient, such as a medicine, vitamin, herbal powder or probiotic, in a shell that is easy to swallow and dissolves in the stomach.
What are hard gelatin capsules made of?
Pharmaceutical-grade gelatin and purified water, with approved colourants and opacifiers for coloured shells. Ours are made from TSE/BSE free bovine hide gelatin.
Can I fill empty capsules at home or in a small business?
Yes. A manual capsule filling machine makes it quick and consistent. See our guide on how to fill empty capsules by hand.
Which capsule size is most common?
Sizes 0 and 00 are the most widely used. Size 0 holds about 544 mg and size 00 about 720 mg of a typical powder blend.
Can hard gelatin capsules hold liquids?
Not water-based liquids, which dissolve the shell. Hard gelatin capsules are designed for powders, granules, pellets and mini-tablets.
Need empty hard gelatin capsules?
Universe Capsules manufactures empty hard gelatin capsules in sizes 000 to 5, in plain, printed, metallic and pearl finishes. Tell us your product and we will recommend a size and send samples.
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