My Mom used to give me cod liver oil with ground up goat bones becaues she thought I was getting rickets. Dad said I never had rickets but I can still remember the horrible taste fifty some years later of that horrible stuff.
There is some danger involved with taking cod liver oil but it didn't kill me.
I've read lots of warnings about cod liver oil recently. UC of Berkely has this to say about it: Just one teaspoon of cod liver oil has 4,500 IU of A, for instance, and the standard dose is one to three teaspoons a day. Capsules of cod liver oil contain less oil, but the vitamin can still add up, especially on top of the amount you get from foods and from a multivitamin, if you take one. Recent studies have found that as little as 6,000 IU of vitamin A daily can interfere with bone growth and promote fractures. And women of childbearing age should not exceed 10,000 IU of vitamin A because of the risk of birth defects. Cod liver oil is made from livers, of course. The liver is a filter, so toxins (such as PCBs) get concentrated there. Thus cod liver oil is more likely to be contaminated than other fish-oil supplements.
If you want to try fish oil supplements, avoid cod liver oil—and talk to your doctor first.