CVS Health Corp. is dropping Viagra, the erectile dysfunction drug manufactured by Pfizer, from its formulary or the list of drugs covered by its insurance benefits.

The exclusion of Viagra in CVS' coverage will take effect in 2016. CVS pharmacies, however, will continue to sell Viagra to anybody whose health plan covers the blue pill or to consumers who are willing to pay for its full price, Bloomberg reports.

"I want to make sure it is clear that this does not impact availability of the drug in our CVS/pharmacy stores. It is related to our standard formulary for those payors whose pharmacy benefits we manage as their PBM through CVS/Caremark," CVS spokesperson Christine Cramer told CNBC.

Companies who use CVS for their drug insurance benefits can opt for exceptions to the formulary.

Meanwhile, the health company assures patients that Cialis, an erectile dysfunction medicine manufactured by Eli Lilly & Co., will continue to get coverage.

"As always, clinical acceptability of the drugs included in the standard formulary is among our primary considerations, enabling us to continue to provide plan members with access to high-quality products within all covered classes of drugs," Cramer said, adding that "Equally effective products with lower overall costs remain available on the formulary," CNBC reports.

CVS did not offer any explanation as to why it is excluding Viagra from its list of covered drugs. Viagra is not expected to face generic competition until 2017.

With CVS Health - the second largest pharmacy benefits company in the U.S. - dropping Pfizer's blue pill, many are wondering if the move will affect Pfizer's shares. On Wednesday, Pfizer's shares went up 0.15 percent after CVS announced its decision to stop covering Viagra, according to The Street.

"Pfizer is committed to ensuring patient access to our medicines. Viagra continues to be available to millions of patients in the marketplace, including many patients whose pharmacy benefit is managed by Caremark," Pfizer CEO Steve Danehy told Bloomberg.

Express Scripts Holding Co., CVS' biggest competitor, will still cover Viagra and Cialis in 2016.