Fish oil capsules too big to swallow? Are there other forms?

Yes, there are other forms. Fish oil comes in several forms besides soft capsules, and fish itself is a food source of EPA and DHA. Which form fits a particular person depends on how well they swallow and which medicines they take, so ask a pharmacist before changing. England's NHS also advises not to open capsules or alter a medicine without advice.

This article explains why the capsules are often large, what each form is, what studies have found about difficulty swallowing pills, and when to see a doctor.

Why are fish oil capsules often so large?

Fish oil is a liquid oil, so it cannot simply be pressed into a tablet. It is usually sealed inside a soft shell.

Oil sealed inside a soft shell

MeSH, the medical vocabulary of the US National Library of Medicine, describes capsules as hard or soft soluble containers used for taking medicine by mouth. Fish oil, being liquid, is usually held in the soft kind: a sealed, soft shell. The size of the capsule follows how much oil it holds.

How large is large?

There is no size rule written for fish oil, but there is one for generic medicines. In its 2022 guidance on the size and shape of generic tablets and capsules, the US Food and Drug Administration recommends that the largest dimension of a tablet should not exceed 22 mm and that capsules should not exceed a standard 00 size. The guidance says people who find tablets and capsules hard to swallow frequently cite size as the main reason, and that children, adolescents and older people are more likely to have difficulty.

How common is difficulty swallowing pills and capsules?

It is more common than many families expect, and it is often not mentioned to anyone.

Older people in Thailand

A study from the Regional Health Promotion Center 7 Khon Kaen and Khon Kaen University, published in 2021, interviewed 874 older people at community hospitals in northeastern Thailand in late 2019, using a 10-item screening questionnaire. Their average age was about 70, and 66% were women. Of them, 11.4% had swallowing problems. The most common were food sticking in the throat, needing effort to swallow and choking. The survey covered one health region and was based on a questionnaire, not a swallowing test.

People taking medicines

A study from the University of Heidelberg, published in 2013, surveyed 1,051 people at 11 general practices in Germany who took at least one tablet or capsule. 37.4% reported having had difficulty swallowing tablets and capsules, and most of them had not been identified by their doctor. Of those with difficulty, 58.8% had already changed how they took their medicines, for example in ways that may alter safety. The study was in one country and relied on questionnaires.

What have studies found about pill size and swallowing?

A study from Keio University in Japan, published in 2024, used questionnaire answers and medicine records from a smartphone app. It found that people taking large tablets or capsules were more likely to report difficulty swallowing, and size was a common reason given. The authors note that only smartphone users took part. A University of São Paulo study, published in 2024, filmed 49 healthy adults swallowing capsules on X-ray video. Capsule size did not change how long the capsules took to pass through the mouth and throat.

The FDA guidance and the three studies above are general information about tablets and capsules, not studies of fish oil itself.

What forms of fish oil are there?

The same oil can be held in different ways. The differences below are definitions of each form, not a ranking.

The form and the oil are different things

The form describes the shell and how the oil is held. What the oil is depends on two other things. The first is where it comes from: the body of fish, fish liver such as cod liver, krill, or algae. The second is the chemical form of the omega-3s. The NIH Office of Dietary Supplements (ODS) lists natural triglycerides, ethyl esters, re-esterified triglycerides, phospholipids and free fatty acids.

Emulsions

MeSH describes emulsions as mixtures formed by combining two liquids that do not mix, such as oil and water. It notes that emulsions of fat in water are usually liquid, like milk, while emulsions of water in fat tend to be creams. In an emulsified fish oil, the fish oil is the part spread through the liquid.

Cod liver oil is a different oil, not a different form

Cod liver oil comes from the liver rather than the body of the fish, and ODS notes that cod liver oil supplements also provide vitamin A and vitamin D. It is a different oil, whatever form it comes in.

Can a capsule be cut or opened?

Do not decide this on your own.

The following is general information about tablets and capsules. England's NHS says not to crush pills, open capsules or alter your medicine without getting medical advice, and that a pharmacist can tell you about other versions that might be available, such as a liquid, and whether a tablet or capsule can be crushed, divided or opened. The German study above found that more than half of the people who had difficulty swallowing had already changed how they took their medicines, which is why asking first matters.

Can fish give EPA and DHA as food?

Yes. Fish and seafood are the main food sources of EPA and DHA. ODS explains that the body makes them from ALA, the omega-3 in plants, only to a very limited extent.

EPA and DHA in some fish

The figures below are from the ODS table, per 3 ounces (about 85 g) of cooked food.

For more fish, see What is omega-3? How much EPA and DHA is in fish oil?

How much fish Thai people eat

A Ghent University study of Thai fisheries, published in 2021, put the current average Thai intake of fish and shellfish at 32 g a day, compared with 28 to 30 g a day in healthy and sustainable dietary recommendations. It is a national average based on supply data, so it says nothing about what any one person eats.

Fish that is easy to eat

England's NHS advises at least 2 portions of fish a week, including 1 of oily fish, with a portion of around 140 g. Oily fish include salmon, sardines, mackerel and trout. For older people who find chewing or swallowing hard, soft dishes such as steamed fish, fish in clear soup or fish porridge, with the bones removed, may be easier to eat.

When should we talk to a doctor or pharmacist?

Signs to see a doctor

England's NHS says that if a person also has difficulty swallowing food and drink, not just pills, they should not try pill-swallowing techniques on their own and should speak to a pharmacist or doctor.

In the Thai study above, the most common swallowing problems among older people were food sticking in the throat, needing effort to swallow and choking. If your parent has any of these, see a doctor.

Questions for the pharmacist

• which forms are available for the product, and which suits your parent's swallowing
• whether the capsule can be opened, cut or mixed with anything
• whether it fits with the medicines your parent already takes

Fish allergy and medicines

The US Food and Drug Administration lists fish and crustacean shellfish among the major food allergens, and krill are crustaceans. ODS notes that omega-3 supplements such as fish oil may interact with some medicines. If your parent has a fish or shellfish allergy or takes regular medicines, talk to a doctor or pharmacist first.

If you are pregnant or breastfeeding, or take regular medicines, speak to a doctor or pharmacist before taking dietary supplements.

Dietary supplements are not intended to prevent, treat or cure any disease.