Gelatin.
Accidental overdose of iron containing products is a leading cause of fatal poisoning in children under 6. Notice: this product contains buckthorn and senna. Read and follow directions carefully. Do not use if you have or develop diarrhea, loose stools, or abdominal pain because buckthorn and senna may worsen these conditions and be harmful to your health. Consult your physician if you have frequent diarrhea, if you are pregnant, nursing, taking medication or have a medical condition. Clear band and tamper evident seal under cap. Do not use if broken.