Brief Answer:
Most likely allergic reaction to cod liver oil.

Detailed Answer:

Hello,

Cod liver capsule is taken from extracts of cod fish liver which is rich in omega 3 fatty acids and fat soluble vitamins of A and D. It is used to treat inflammatory conditions such as joint and muscle disorders, have effects to decrease blood pressure.
It does not cause joint pain or have no such side effects. Fat soluble vitamins (A and D) may cause side effects from overdose in people who are taking cod liver oil capsules high doses for months.

Joint pain you experienced is likely have allergic origin. It is likely precipitated by certain ingredients of cod liver oil. You might have allergic joint pain to those ingredients.
Please give me more information by answering the following questions so that I can guide you better:
Have you experienced the pain on the first day of taking the capsules? Which joints did you experience the pain? Was the pain constant or on and off? Have you experienced any other symptoms? Are you still experiencing the pain? Are you taking any other medicine? Do you have any joint/bone or muscle disorders?

Also feel free to ask me if there is anything else you need to know.
Thank you

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Brief Answer:
Symptoms are highly suggestive of allergic arthritis

Detailed Answer:

Hi,

Sudden start of the pain on the first day after taking Cod liver capsule, affecting multiple joints and ceasing the pain after stopping the supplement is highly suggestive of allergic arthritis. You should avoid taking cod liver capsules.

Specific types of substances in the food or in medications can cause allergic arthritis. It progresses with formation of antibodies by an organism against joint tissues which lead to the inflammation of the joints.

In the start of allergic arthritis patients often experiences pain in the multiple joints: small (finger/toe joints) to larger joints (wrists, elbows, hips, knees, and ankles) may get involved.
Allergic arthritis is different from other forms of arthritis that in allergic arthritis joint pain occurs within a short time after ingestion of a medication or a food. Treatment is avoiding the medicine or food that causes body allergic reaction against it. In the mild form or initial period of allergic arthritis usually symptoms cease after stopping the offending medication. So you can stop cod liver oil. If the joint pain continues anti-inflammatory medications should be prescribed.

Hope the information is helpful for you. Please, let me know if I can assist you further.
Thank you

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