Westhroid is NOT the same as WP Thyroid, but it is the same as NatureThroid. All three thyroid preparations, Westhroid, WP Thyroid, and NatureThroid are manufactured by RLC Labs. The difference between Westhroid and WP Thyroid is that WP Thyroid is one of the purest thyroid preparations available, containing only 2 all-natural inactive ingredients, and it is also available in 8 strengths whereas Westhroid is only available in 5 strengths.