What happens if I take too much cod liver oil? Risks, Symptoms, and Precautions

January 1, 2026 •

4 min read

According to Healthline, consuming more than one tablespoon of cod liver oil daily can lead to excess vitamin A intake, risking toxicity. Understanding what happens if I take too much cod liver oil is crucial for preventing serious health complications, as fat-soluble vitamins can accumulate in the body.

Quick Summary

Excess cod liver oil intake can cause toxicity from its fat-soluble vitamins A and D, leading to symptoms like headaches, nausea, and potentially severe organ damage. It can also increase bleeding risk due to its omega-3 content.

Key Points

Fat-Soluble Vitamin Toxicity: The biggest risk of taking too much cod liver oil is toxicity from its high concentration of fat-soluble vitamins A and D, which accumulate in the body.
Hypervitaminosis A Dangers: Excess vitamin A can cause severe headaches, dry skin, vision changes, and, in severe chronic cases, irreversible liver damage.
Hypercalcemia from Vitamin D: Too much vitamin D leads to hypercalcemia (excess calcium), with symptoms including nausea, confusion, kidney stones, and potential heart arrhythmias.
Increased Bleeding Risk: The omega-3 content in high doses of cod liver oil has a blood-thinning effect, increasing the risk of bruising and bleeding, especially for those on anticoagulant medication.
Follow Dosage Guidelines: It is crucial to adhere strictly to the recommended dosage, as even one extra tablespoon can significantly increase your risk of surpassing safe vitamin intake levels.
Distinguish from Fish Oil: Unlike regular fish oil, cod liver oil contains significant amounts of vitamins A and D, which is why its dosage must be monitored more closely to avoid toxicity.

The Primary Dangers: Vitamin A and D Toxicity

Cod liver oil is prized for its high content of vitamins A and D, along with omega-3 fatty acids. While beneficial in moderation, these fat-soluble vitamins can build up in the body's tissues over time, posing a significant risk of toxicity, known as hypervitaminosis. Unlike water-soluble vitamins that are easily flushed out, excess fat-soluble vitamins remain in the body, which is the root cause of overdose concerns with cod liver oil.

Hypervitaminosis A: Symptoms and Consequences

Since cod liver oil is derived from the liver, it contains preformed vitamin A (retinol), which can be directly toxic at high doses, unlike beta-carotene from plants. The tolerable upper intake level (UL) for vitamin A is 3,000 mcg per day for adults, and a single tablespoon of cod liver oil can contain nearly half this amount.

Common symptoms of acute or chronic hypervitaminosis A include:

Headaches and irritability
Nausea and vomiting
Blurry vision
Dry, rough, or peeling skin and cracked lips
Bone and joint pain
Hair loss, including eyebrows

More severe long-term effects can include:

Liver damage, hepatomegaly (enlarged liver), and even cirrhosis
Increased intracranial pressure, which can cause severe headaches and vision changes
Increased risk of osteoporosis and hip fractures over time
Birth defects in pregnant women

Hypervitaminosis D: Symptoms and Consequences

While rarer than vitamin A toxicity, excessive vitamin D intake can also be dangerous, leading to hypercalcemia, or too much calcium in the blood. The tolerable upper intake level (UL) for vitamin D is 4,000 IU (100 mcg) per day for adults, and some doses of cod liver oil can approach or exceed this. Hypercalcemia primarily impacts the cardiovascular and renal systems.

Symptoms of vitamin D toxicity include:

Fatigue and weakness
Nausea, vomiting, and loss of appetite
Constipation
Excessive thirst and urination
Confusion or disorientation
Arrhythmias or irregular heart rhythms

Long-term complications of high calcium levels include:

Hardening of arteries and soft tissues
Kidney stones and permanent kidney damage
Bone loss

Increased Risk of Bleeding

Cod liver oil is rich in omega-3 fatty acids, which have natural blood-thinning properties. While this can be beneficial for some, taking excessive amounts, especially more than 3 grams daily, can increase the risk of bleeding. This is particularly dangerous for individuals on anticoagulant medications (e.g., warfarin) or those preparing for surgery. A sign of this effect can be an increase in nosebleeds or bruising.

Other Common Side Effects

Beyond the risks of vitamin toxicity and bleeding, an overdose of cod liver oil can cause more common, yet uncomfortable, side effects.

These can include:

Stomach upset, indigestion, and diarrhea
Nausea
Burping or a persistent "fishy" aftertaste
Heartburn or acid reflux, especially with large doses

Cod Liver Oil vs. Regular Fish Oil

Understanding the key differences is critical for supplement safety. Cod liver oil is derived specifically from the liver and contains high levels of vitamins A and D, in addition to omega-3s. In contrast, regular fish oil is made from the flesh of oily fish and contains omega-3s without the high vitamin A and D content.


Feature	Cod Liver Oil	Regular Fish Oil
Source	Liver of cod fish	Flesh of oily fish (e.g., mackerel, salmon)
Primary Omega-3 Content	Yes (EPA and DHA)	Yes (EPA and DHA)
Key Vitamins	High in Vitamin A and Vitamin D	Low or no significant vitamins A and D
Toxicity Risk	High risk of Vitamin A and D toxicity in large doses	Little to no risk of vitamin toxicity
Main Concern	Overdose of fat-soluble vitamins	Overdose of omega-3s (bleeding risk)

What to Do in Case of Overdose

If an excessive amount of cod liver oil has been consumed, particularly by a child, or if symptoms of toxicity develop, it is important to seek medical attention immediately. Treatment will likely involve supportive care to manage symptoms, but prompt action can prevent serious complications. Discontinuing the supplement is the first step in managing chronic hypervitaminosis.

Conclusion: How to Stay Safe with Cod Liver Oil

While cod liver oil is a potent and beneficial supplement for many, the risk of toxicity from fat-soluble vitamins A and D is a serious concern with high or prolonged intake. Adherence to the recommended daily dosage on the product label is paramount, as exceeding these amounts significantly raises the risk of liver damage, hypercalcemia, and other adverse effects. Always consult a healthcare professional before starting any new supplement, especially if you are pregnant, have a pre-existing medical condition, or take other medications. For more in-depth information on vitamin A toxicity, consult the resources from the National Institutes of Health. Staying informed about potential risks and respecting dosage limits is the best way to safely harness the benefits of this supplement.

Frequently Asked Questions

The initial signs of an overdose or chronic excessive intake often include mild digestive issues like nausea, upset stomach, or diarrhea, a persistent 'fishy' burp, and headaches.

Yes, it is possible to get vitamin A toxicity (hypervitaminosis A) from taking too much cod liver oil, as it contains a high concentration of preformed vitamin A (retinol), which can accumulate to toxic levels in the body over time.

The safe upper limit is determined by the vitamin A content. The tolerable upper intake level (UL) for vitamin A is 3,000 mcg per day for adults, so dosage should be kept within this limit, with typical recommendations being no more than 1 to 2 teaspoons per day.

Yes, children are more sensitive to vitamin A toxicity and have much lower safe upper limits. The UL for a child aged 4-8 is 900 mcg per day. A child on cod liver oil should be monitored closely by a pediatrician.

Yes, in high doses, the omega-3 fatty acids in cod liver oil can have a blood-thinning effect. This can increase the risk of bruising and bleeding, particularly if you are also taking anticoagulant medication.

If you suspect an overdose, especially if you experience severe symptoms like persistent nausea, headaches, or confusion, you should seek immediate medical attention. For less severe symptoms, stopping the supplement is the first step.

Cod liver oil can lower blood pressure, and when combined with blood pressure medication, it can cause your blood pressure to drop too low. It's essential to monitor your blood pressure and consult your doctor before combining them.