Active Iron is suitable for vegetarians lactose-free. Clinically proven better absorption of ferrous sulfate. In addition, no unfavourable side-effects were reported for Active Iron. GENTLE AND NON-CONSTIPATING: Active Iron Advance avoids common side effects and discomfort such as nausea and constipation; It is so gentle, it can be taken on an empty stomach avoiding digestive discomfort; Active Iron’s patent protected formula protects the stomach from the irritating effects of iron, making it easy to tolerate.