Coral calcium: Safe for people with shellfish allergies?

If you have shellfish allergies, you shouldn't take coral calcium. Coral calcium, which is obtained from ocean coral reefs, can trigger allergic reactions, such as hives, breathing problems and swelling, in people with shellfish allergies. There's no scientific evidence that coral calcium is better than other forms of calcium. Also, some coral calcium products manufactured in countries outside the United States have been found to contain high levels of lead.