Fish oil capsules: what side effects are possible?

Fischölkapseln: Welche Nebenwirkungen sind möglich?

Fish oil capsules are dietary supplements that have some positive effects on our human body. On the one hand, they should not only lower high blood pressure, they should also have positive effects on our skin and immune system. But are the fish oil capsules so positive or do they also have side effects?

How can I prevent these side effects and under what circumstances should I not take fish oil capsules? In our guide we will show you what you should look out for with fish oil capsules and what side effects they have. We want to clear up your doubts on the subject and make it easier for you to decide whether you should take fish oil capsules and what you should pay particular attention to.

the essentials in brief

  • Fish oil capsules consist of omega-3 fatty acids, which are very important for our human body.
  • Side effects that may occur include insomnia, increased bleeding tendency and diarrhea or heartburn.
  • The dosage of fish oil capsules is the alpha and omega. You should definitely not consume too much because the side effects of this are immense.

Fish oil capsules and their side effects: What you should know

Fish oil capsules have been talked about for years and are taken as a dietary supplement by various groups of people. But what is behind the capsules and what side effects do they produce? In this section of our guide, we will answer all of these questions for you.

What are fish oil capsules?

Fish oil capsules are dietary supplements. These are omega-3 fatty acid tablets. Among other things, they are used to advertise that the additional intake of fish oil capsules can cause various positive health effects, such as maintaining normal blood pressure.

Basically, fish oil capsules consist of omega-3 fatty acids , which are essential for human life. Since our bodies cannot produce them, we have to absorb them through our food.

What Side Effects Could Fish Oil Capsules Cause?

The omega-3 fatty acids in fish oil capsules have positive effects but also negative ones. In this table we have summarized the side effects for you that could occur when taking it.

side effect Explanation
increased tendency to bleed Excessive intake of fish oil can lead to either increased nosebleeds or bleeding gums. If this is one of the side effects you have experienced, you should reduce your intake. In general, it can also inhibit the formation of blood clots in healthy adults, increasing your risk of bleeding. It can also lead to reduced blood clotting. For example, if you are taking medication that should thin your blood, talk to your doctor about taking fish oil capsules. (1,2)
low blood pressure Fish oil can produce the effect of lowering blood pressure. This is beneficial for people who suffer from high blood pressure, for example. However, this effect can be dangerous for people who already suffer from low blood pressure. The fish oil capsules also work there. (3.4)
high blood sugar Ingesting omega-3 fatty acids in fish oil capsules can cause your blood sugar levels to rise. This effect can be bad for diabetics. Once again, it depends on the dose. At a high dose, it can cause blood sugar levels in type 2 diabetics to rise by 22% in just a few weeks. So if you take a lower dose, it should not lead to an increase in your blood sugar level. (5.6)
heartburn Side effects that may occur with fish oil capsules include nausea, heartburn or acid regurgitation, upset stomach, and indigestion. As with the other cases, a lower dose can negate these side effects.(7,8)
Diarrhea A well-known side effect of fish oil is diarrhea. If this is the case for you, you should either stop taking fish oil capsules or take them with your meals.(9,10)
weight gain While fish oil capsules help you lose weight, taking too much can actually slow down your weight loss instead of stimulating it. Fish oil capsules still have calories, and you should factor that in.(11,12)
insomnia One side effect that can occur when taking fish oil capsules is insomnia. A high dose can also trigger anxiety.(13,14)
stroke A high intake of omega-3 fatty acids in the form of fish oil capsules can increase your risk of having a stroke. As already established, the formation of blood clots can be inhibited. This increases the risk of suffering from a hemorrhagic stroke. (15,16,17)
vitamin toxicity The fish oil capsules provide omega-3 fatty acids and these in turn are rich in vitamin A. However, an excessive amount of vitamin A can cause negative effects such as joint pain, nausea, dizziness and skin irritation. However, a long-term overdose can lead to more serious health problems, such as liver failure.(18)

However, to be on the safe side, you should always consult your doctor.

However, you should always keep an eye on the dose. Fish oil capsules also have positive effects on us in a certain amount and for certain health problems such as high blood pressure. The be-all and end-all is the right dose to avoid side effects.

Why do I need fish oil capsules?

The omega-3 fatty acids in the capsules are very vital for our body. Among other things, you absorb these when you eat fish. Basically, fish should be eaten once a week. However, since there are different preferences when it comes to food, there is an alternative to grabbing fish oil capsules.

fish oil capsules

The tablets are not hard like conventional ones. They are felt with fish oil and are therefore softer in consistency. (Image source: Michele Blackwell / unsplash)

Of course you can also take the dietary supplements if you like fish, but don't get around to eating fish every week. In principle, you can also take them if you suffer from health problems, such as high blood pressure or high cholesterol.

Fish oil capsules can help alleviate these symptoms. However, you do not necessarily have to take the supplements as a healthy person. But you shouldn't do without it completely, because omega-3 fatty acids serve, among other things, to ensure the normal and healthy growth of your cells.

When is the best time to take the fish oil capsules to avoid side effects?

It is best if you take fish oil capsules with your meals. However, you should be careful if you consume it in addition to a fish meal. You can take the capsules either before or during your meal.

However, how many pills you should take depends on the brand. So it's best to look at your package insert.

Can too many fish oil capsules be harmful to me?

Basically, taking too many fish oil capsules can cause side effects for you. However, the dose is different for each person. One or two meals a week where fish is eaten is recommended. The amount of around 1500 mg of omega-3 fatty acids should under no circumstances be exceeded per day.

The saying "the more the better" definitely doesn't apply here.

It is therefore best to check the label and make sure that you are not exceeding this amount with the food you are eating. Too much can have side effects such as skin problems, muscle weakness or even depression. (19)

What should I look out for best with fish oil capsules to avoid side effects?

Since these are dietary supplements, there are a few points you should also pay attention to so that you do not have to accept any health consequences. In this table we have listed some important points for you to pay attention to.

Pay attention to Explanation
Purchase of the fish oil capsules Because there are so many different products on the market, you should be careful. These are dietary supplements that you take to benefit your health, not to harm it. There are different price ranges but be careful as the cheap products are not always the best quality products.
Products The omega-3 fatty acids are most commonly found in capsules in the forms DHA and EPA. In principle, all of the fatty acids should be listed for the products. It doesn't matter to differentiate between DHA or EPA. For athletes there is also powder instead of capsules. For children, fish oil also comes in chewable tablet form that has been flavored to make it easier to absorb by bypassing the flavor and size.
as a vegan person If you eat vegan, the usual fish oil capsules are out of the question. There are different plant-based alternatives such as walnuts.
storage Pay particular attention to the expiry date of fish oil capsules. This is still a fish product that should be handled with care. After opening, it is best to store it in the fridge. The omega-3 fatty acids are also very sensitive to light and the packaging should remain well sealed. However, it can lead to the capsules being incorrectly stored by the supplier. If the capsules have burst, then it is not advisable to take them.

How long can I take fish oil capsules without causing side effects?

Basically, you can take fish oil capsules your whole life. However, you should pay attention to the correct dosage and if side effects occur, either reduce the dosage or stop. If you show chronic symptoms, then it would be advisable to stop taking it after three months.

Furthermore, it would be advisable to divide your daily dose into two individual doses, which ensures that your body absorbs the dietary supplement in the best possible way. However, if you are taking other medications, you should contact your doctor and see if taking fish oil capsules as well causes side effects.

Can I open fish oil capsules or are there side effects?

Basically, you can open the fish oil capsules with scissors or something sharp. However, it depends on which brand your capsules are. Some can be opened to allow the contents, in this case the fish oil, to be added to smoothies or other beverages. This neutralizes the taste of the fish oil. In such cases, it is best to ask the pharmacist or look at the label of your capsule packaging.

Do I absolutely have to take fish oil capsules or can I also cover my needs with my food and thus avoid side effects?

You don't have to take fish oil capsules on top of that. A healthy person has no obligation to take these capsules. In principle, you can also cover your need for omega-3 fatty acids with a balanced diet.

salmon with rice

It doesn't matter if you eat a grilled salmon or a can of tuna. Omega 3 provide both varieties. (Image source: Sebastian Coman Photography / unsplash)

On the one hand you can eat fish twice a week, sea fish is preferred, otherwise you can also eat canned tuna, for example. You can also eat almonds daily or use margarine.

Under what circumstances should I not take fish oil capsules to prevent side effects?

Fish oil capsules can worsen your health or have negative effects on you if you are allergic to fatty fish, among other things. You should also avoid the capsules if your fat digestion in the small intestine is disturbed, you suffer from cirrhosis of the liver, your pancreas is inflamed or your gallbladder is enlarged or inflamed.

When belching after taking it, you may smell like fish yourself.

The same applies to you if your kidneys are only working to a limited extent. The same applies if you have to undergo surgery because of high blood pressure or your blood has already stopped clotting. In all these cases you should ask your doctor for his opinion (2,3).

What alternatives are there to fish oil capsules and their side effects?

Because fish oil capsules are not vegan, there are of course alternatives for those of us who eat animal products or generally prefer plant-based products.

algae oil

This is a vegetable oil that was not contaminated with heavy metals or mercury during production. Seaweed is used to make it. Algae oil would therefore be a great alternative for you if you should eat more vegan.

linseed oil

Linseed oil, as the name suggests, is made from flax seeds and is also a vegetable oil. In addition to the omega-3 fatty acids, the ingredients are also vitamin E. However, you should not use linseed oil for frying, but rather pour it over hot or cold food.

Chia seeds

The chia seeds provide, among other things, omega-3 fatty acids, iron and magnesium. These are herbal seeds from the Salvia hispanica plant. You can add them to shakes or add them to your oatmeal for breakfast.


An alternative to the fish oil capsules are fish. You can theoretically consume salmon instead of taking the capsules. This type of fish is also very rich in omega 3. You can either fry the salmon or eat it raw in the form of sushi.


You can also consume walnuts. In addition to potassium, zinc and iron, these also provide omega 3. If you are struggling with the side effects of fish oil capsules, then you can at least fall back on one of these alternatives. With the help of them you can also balance your omega 3 household.


In principle, it is worthwhile for you to take fish oil capsules if you do not get enough omega-3 fatty acids through your food. The same applies if you eat vegan and otherwise do not get any other kind of omega-3 fatty acids. It is a very important part of our body.

However, if you are a healthy person, you do not have to take the capsules in addition to yourself. There are also alternatives that do not cause the side effects. However, be sure to pay attention to your dosage, because an overdose is very dangerous in this case. If you have concerns, it's better to discuss with your doctor whether fish oil capsules would be good for you.


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