I have never once in my life had an allergic reaction to shellfish. Had a delicious crab, shrimp, and scallop dinner just the other night and felt great. When researching this product, i remember shellfish allergy being one of the caveats. I did not think anything of it because, again, i have never once had an allergic reaction to shellfish. Took ONE capsule of this product and became ill. Throat became sore. Tongue was overcome with a strong metallic taste and felt almost numb. Breathing became labored. Head began to be overcome by the feeling of being ill. As i was not initially certain that it was this product (although it was the only new item introduced into my body in the last 48 hours), i waited the better part of the day for the symptoms to pass. As they did, not wanting to rush to premature judgment, i tried a second, different coral calcium product i had ordered at the same as this product, the other product is Best Naturals Coral Calcium Plus 1000 mg 250 Capsules from Amazon. It is a smaller dose, one capsule. Same result, same symptoms. Became sick. This NOW Coral Calcium Plus,250 Veg Capsules is also not advertised/labeled correctly on the Amazon product page, see the attached images. Cannot image what would have happened if i had taken a full dose (2 capsules). Maybe a visit to the emergency room? Metallic taste still lingers, throat still a bit sore. Lungs feel raw. Still not back to full health. Returning for full refund