Fairness in Orphan Drug Exclusivity Act This bill limits which orphan drugs may be granted a market exclusivity period by the Food and Drug Administration (FDA). (Generally, an orphan drug is one that is not economically viable because of the rarity of the disease that it treats; the sponsor of an FDA-designated orphan drug may be granted various incentives, such as a seven-year period in which the FDA may not grant market approval to a different sponsor for the same drug to treat the same disease.) Specifically, when determining whether to grant an exclusivity period to a drug that has orphan status due to low expected sales, the FDA must consider the sales of all drugs from the sponsor that are covered by the same orphan drug designation.