The recent stock market sell-off appears to have fizzled out and now could be a great time for long-term investors to put some of their cash to work.

Three Motley Fool contributors think they've found fantastic growth stocks to buy in August. Here's why they picked Eli Lilly (NYSE: LLY) , Novo Nordisk (NYSE: NVO) , and Vertex Pharmaceuticals (NASDAQ: VRTX) .

A behemoth that could double in size

David Jagielski (Eli Lilly): Growth investors might be tempted to look for small-cap stocks in the hopes of maximizing long-run returns, but one of the best growth stocks in healthcare is also the largest: Eli Lilly. At a market cap of around $800 billion, it's likely only a matter of time before it becomes the first healthcare stock to reach a $1 trillion valuation. I think the stock could go far higher than that, potentially doubling within the next five years.

Lilly's latest quarterly results highlighted why this is a fantastic growth stock to buy. It has been a little over two years since the U.S. Food and Drug Administration (FDA) approved diabetes medication Mounjaro. The drug's sales topped $3.1 billion in Lilly's most recent quarter, which ended on June 30. Regulators approved Zepbound (which contains the same active ingredient as Mounjaro) for weight loss in November of last year. It's bound to be another huge drug for Eli Lilly, already raking in $1.2 billion in revenue last quarter.

The only thing stopping Eli Lilly these days is its constrained capacity. There's simply too much demand for the company's diabetes and weight loss medications. Lilly is working feverishly to expand capacity so that it can sell more of these highly coveted products. And investors also shouldn't forget the company's recently approved early Alzheimer's treatment, Kisunla, which is likely to be yet another blockbuster drug.

Eli Lilly is not only a safe healthcare stock to invest in but it's a growth beast, with loads of potential in the long run, and the business is only going to get far more valuable in the years ahead.

A pharmaceutical giant defying gravity

Prosper Junior Bakiny (Novo Nordisk): Investors looking for a stock firing on all cylinders need look no further than Novo Nordisk. This leading drugmaker has been flying over the past five years, delivering strong financial results, making steady clinical progress, and performing better than most of its similarly sized peers.

Novo Nordisk likely won't slow down significantly anytime soon. The company's two main growth drivers, weight loss medicine Wegovy and diabetes therapy Ozempic, are still going strong. These have become famous brands, a feat more common in the tech industry than in pharmaceuticals. And while Novo Nordisk's success is attracting scores of competitors, the company is likely to remain near the top of the fast-growing anti-obesity market.

Novo Nordisk boasts several highly promising candidates in this area . Perhaps one worry some investors have is that Eli Lilly is too reliant on its diabetes and obesity portfolio. People probably can't name drugs in other fields that significantly contribute to its top-line growth. That's because there aren't any. However, Novo Nordisk is looking to diversify its lineup. Its pipeline features potential medicines for Parkinson's, hemophilia, sickle cell disease, thalassemia, and other conditions.

Even if other companies eat up some of its market share in its core areas, Novo Nordisk should eventually successfully launch at least a few blockbusters elsewhere to compensate. Don't underestimate the drugmaker's innovative potential. It is largely responsible for its current success and will continue driving the stock to greater heights over the long run. Novo Nordisk is an excellent stock to buy this month, or any month, for that matter.

Growth, growth, and more growth

Keith Speights (Vertex Pharmaceuticals) : Growth hasn't been a problem whatsoever for Vertex Pharmaceuticals in recent years. The company enjoys a monopoly in treating the underlying cause of the rare genetic disease cystic fibrosis (CF). Its CF sales could accelerate if Vertex's vanzacaftor triple-drug combo receives FDA approval, which could be on the way by early 2025.

Vertex is poised to generate further growth outside of CF. The launch of Casgevy as a one-time treatment for rare blood disorders sickle cell disease and transfusion-dependent beta-thalassemia is still ramping up. Casgevy is the first CRISPR gene-editing therapy to receive FDA approval.

More growth (and I'd go as far as to say much more growth) could be coming soon. Vertex awaits FDA approval of suzetrigine for the relief of acute pain. As a non-opioid, I think the drug should have tremendous commercial potential.

Vertex is evaluating inaxaplin in a late-stage clinical study targeting APOL1-mediated kidney disease (AMKD). There are currently no approved therapies for treating the underlying cause of AMKD. The company's recent acquisition of Alpine added povetacicept to its pipeline. The experimental drug is another late-stage candidate targeting kidney disorders.

Perhaps best of all, Vertex's valuation doesn't reflect its tremendous growth prospects. The stock's price-to-earnings-to-growth (PEG) ratio is a low 0.67. Any stock with a PEG ratio below 1.0 is considered to be attractively valued.

Before you buy stock in Eli Lilly, consider this: