There's at least one downside to the market gains this year: Many stocks aren't as attractively valued as they once were. That doesn't mean that you can't find plenty of bargains, though.

While attractive valuations can be spotted in nearly every sector, healthcare looks especially promising right now. Here are three healthcare stocks that are too cheap to ignore (listed in alphabetical order).

1. Pfizer

Pfizer (PFE 0.91%) ranks as one of the biggest drugmakers in the world. But while its market cap is high, its valuation isn't. Pfizer's shares currently trade at less than 10.5 times expected earnings. The company's enterprise value (EV) is only 6.28 times its earnings before interest, taxes, depreciation, and amortization (EBITDA).

It's no secret why Pfizer stock is relatively cheap. The company's COVID-19 vaccine Comirnaty and antiviral therapy Paxlovid face significant uncertainty going forward. Pfizer projects that its total revenue could sink 33% this year because of the declining sales of the two products.

Unfortunately, lower COVID-19 revenue isn't Pfizer's only concern. The company also will lose exclusivity for several of its top-selling products in the coming years, including Eliquis, Ibrance, Xeljanz, Xtandi, and Vyndaqel. 

However, Pfizer has several new products on the market, and more are expected to launch in the near future. The company thinks these products will generate more-than-enough revenue to offset the anticipated sales declines from its products losing exclusivity. Pfizer also plans to put its big cash stockpile to use in making business-development deals to boost its growth.

2. Viatris

Viatris (VTRS 0.45%) shares a couple of things in common with Pfizer. First, the generic-drug maker was part of Pfizer before a 2020 spinoff. Second, Viatris stock is cheap. Its shares trade at 3.93 times expected earnings. The company's EV-to-EBITDA multiple is 7.34.

One key factor behind Viatris' low valuation is that its growth prospects aren't impressive. The company's decision to sell most of its global biosimilar assets to Biocon in 2022 made achieving growth even more difficult.

However, the company's business generates steady cash flow. It also has some growth opportunities, notably including its eye-care portfolio and pipeline that's projected to add more than $1 billion in annual net sales by 2028.

Income investors will especially like Viatris' dividend yield of over 3.9%. The company plans to begin returning at least 50% of its free cash flow to shareholders through dividends and share buybacks beginning in 2024.

3. Walgreens Boots Alliance

Walgreens Boots Alliance (WBA 0.61%) stands out as another attractively valued healthcare stock. Its shares trade at 7.41 times expected earnings. The pharmacy giant's EV-to-EBITDA multiple is only 7.86.

Competition has always been fierce for Walgreens. Amazon's entrance into the retail-pharmacy market still causes some investors to worry. The company's Boots business in the U.K. has struggled in recent years, and Walgreens' top and bottom lines deteriorated year over year in the latest quarter.

The good news, though, is that Walgreens has made some smart strategic acquisitions. Its U.S. retail pharmacy business remains strong. The company expects accelerating growth in the future.

Walgreens also offers an attractive dividend yield of nearly 5.2%. It has increased the dividend for 47 consecutive years.

Paying attention doesn't necessarily mean paying up

All three of these stocks are too cheap for investors to ignore. However, paying attention doesn't necessarily mean you have to pay up and buy these stocks.

I think that income investors might like Pfizer, Viatris, and Walgreens. Growth investors, on the other hand, will probably want to look elsewhere.

My view is that Pfizer is the best pick in this group. If the big drugmaker's new products and business-development deals work out as well as the company expects them to, Pfizer could be able to deliver total returns that beat the market over the next decade.