Gelatin capsules are small shells made from gelatin that are used to enclose various medications and nutritional supplements. Their main goal is to make it easier for people to swallow pills, particularly those that are large or might otherwise be dry and difficult to get down the throat. Gelatin is typically very smooth and also resists reacting or mixing with other substances, so it’s a safe and usually quite inexpensive addition to many pills. It can also help manufacturers get an accurate and uniform dose into each pill. Fluid-filled capsules are usually made of just one piece of continuous gelatin covering, though solids may include two interlocking pieces. In either case, most capsules are made from “natural” gelatin, which often has its origins in pig, horse, and other animals’ bones and hooves. Synthetic and vegetable-based options are available in some areas, but not always — and not always inexpensively, either.
Capsules have advantages for both manufacturers and consumers. Drug and supplement makers often choose to coat their pills in gelatin because the covering is a good way to contain the active ingredients. This is particularly important for pills that are made of liquid or powder. Gelatin is nearly odorless and almost always tasteless, and it typically does not cause digestive problems. In most cases it won’t interact with other drugs, either, and it won’t usually break down or erode under normal environmental conditions. Once in the stomach it will typically dissolve rather quickly, which allows for an even release of the contents.
The coating can also make it easier to swallow pills that are either very large or that contain unpalatable or foul-tasting ingredients. Substances like fish oil, for instance, can be difficult to ingest, so putting them in a neutral-tasting gelatin capsule makes them easier for some people to get them down. Similarly, certain spices used as supplements, like cayenne pepper and cinnamon, can be easier to consume in capsule form.
Another possible advantage of gelatin capsules is their uniform dosage. Commercial drug capsules are usually filled by machine and generally have the most accurate dosage of any manufacturing process. There are devices available through some retailers that allow the consumer to fill their own capsules at home, too. These can be useful if a large number of capsules must be filled on a regular basis, or if the contents contain finely ground powders.
Most capsules come in one or two pieces. Single capsules are used to hold many commercial drugs, particularly those that are filled with liquid or measured powders. Solids may be coated with two pieces, which are often different colors: half of the pill may be red, for instance, and the other half white. This is more common for pills that are solids or pressed solids. Capsules make them smoother, but aren’t usually essential for holding anything in.
Empty two-piece capsules can sometimes also be purchased by consumers and filled with a more personalized combination of supplements, such as vitamins, minerals, and powdered nutrients. This is often less expensive than buying pre-filled capsules, and has the added advantage of allowing the consumer to customize pills to his or her personal needs.
How They’re Made
Gelatin is usually derived from the bones and hooves of pigs, horses, and cows, although it can also be made from other animals such as fish. This can make the capsules unsuitable for vegetarians and people who avoid consuming certain animals for religious reasons. Some people are also allergic to animal gelatin, and there have been some concerns that gelatin derived from cows may be infected with Bovine Spongiform Encephalopathy, also known as “mad cow disease,” and this has led some people to worry that pills made with this sort of gelatin may carry a disease risk. Experts usually agree that the animal derivatives in gelatin capsules are too small to warrant serious concern when it comes to diseases, though.
Vegetarian capsules can be found in many places, though they aren't always available on every drug. Most are made from a type of cellulose, though other sources, such as the edible polymer called pullulan, can also be used. These are often more expensive than those made from animal products, though, and they may also be harder to find. Gelatin was traditionally the preferred form of capsule, since vegetarian capsules tend to be softer and have a shorter shelf life. Improvements in manufacturing have made vegetarian capsules more like their gelatin counterparts, however, and many researchers are continuing to look for more competitive synthetic alternatives.