Kirkland Signature Extra Strength Acetaminophen Caplets active ingredient is 500 mg. Acetaminophen may be used as a pain reliever/fever reducer for adults and children 12 years and over. Kirkland Signature Extra Strength Acetaminophen Caplets are easy to swallow, aspirin free, caffeine free and gluten free. This product should not be used with other medicines containing acetaminophen.