South Carolina Highway 63 Alternate (SC 63 Alt.) was an alternate route that existed east-southeast of Islandton. It was established in February 1938 as a partial renumbering of SC 63. It was decommissioned in 1947 and downgraded to secondary roads. Its west–east portion is known today as Varnadoe Road. Its south–north portion is known as Adnah Church Road.