Is it safe to take fish oils if allergic to shellfish?

Fish oil supplements are meant to deliver fatty acids, such as omega-3, for their claimed health benefits. Depending on how these fatty acids are separated out, there could be other fish proteins in the supplements. Allergies are usually in response to proteins, so caution should be used if you have a fish allergy. However, if you have an allergy strictly to shellfish and have no problems with fish, it is unlikely that the fish protein would cause an allergic reaction. If you are not sure whether you have a fish allergy in addition to shellfish allergy, you should be cautious about taking fish oil supplements.