While no stock is guaranteed to bring winning returns, established companies with strong businesses and wide moats can be a viable source of portfolio growth for investors through the years. You can find these stocks across a wide range of industries, with one example being the healthcare space.

Healthcare stocks can be considerably less volatile than the average stock, typically because they tend to represent businesses that receive an enviable influx of revenue and profits from products that consumers depend on daily.

Here are two such stocks to consider adding to your portfolio this month and holding for the long haul.

1. Johnson & Johnson

Johnson & Johnson (JNJ -0.46%) is one of the most well-known names in the pharmaceutical industry, with a company history that stretches back nearly 140 years. The company made headlines in 2023 when it spun off its consumer health division, known for brands like Band-Aid, Tylenol, and Benadryl, into a new publicly traded entity called Kenvue.

This move served multiple purposes for Johnson & Johnson, a major one being to divest itself of a business segment that was significantly slower-growing than its pharmaceutical and medical device divisions, thereby hampering overall growth. Another benefit from the sale was that J&J raked in a hefty cash payday of about $13 billion as a result of Kenvue's initial public offering (J&J still owns 9.5% of Kenvue's stock).

Johnson & Johnson reported a whopping $21 billion in sales in the third quarter of 2023 alone, up 7% year over year, while profits for that three-month period totaled $4.3 billion. Broken down by segment, its pharmaceutical division -- powered by heavy hitters like cancer drug Darzalex, plaque psoriasis and psoriatic arthritis drug Stelara, and plaque psoriasis drug Tremfya -- raked in $14 billion of that revenue total, up 5% year over year. And its medical device division saw a nice 10% year-over-year sales bump, totaling $7.5 billion.

Johnson and Johnson is one of those businesses that you can buy, hold, add to, and forget about. In addition to product expansion, the company continues to grow through acquisition, with two recent examples being its 2022 acquisition of Abiomed (known for the world's smallest heart pump) and its planned acquisition of Ambrx Biopharma, which is known for its antibody drug conjugates (targeted cancer treatments).

It has 60 years under its belt of not only paying, but raising its dividend, and that dividend has increased 80% over the trailing decade, boasting a current yield of around 3%. This isn't a get-rich-quick stock, but few companies with staying power in your portfolio will be. On the other hand, if you're looking for a quality well-diversified business that can lend steady returns to your portfolio with time, Johnson & Johnson is a top healthcare stock to consider.

2. AbbVie

AbbVie (ABBV -4.58%) stock hasn't delivered the mouthwatering financial or stock performance that some healthcare investors might have wished in recent months, but the pharmaceutical giant still packs a powerful punch when you look at the big picture. First, this stock has not only paid, but also raised its dividend every year for over 50 years and counting. Its current yield is just shy of 4%.

AbbVie pays (and raises) that dividend through economic thick and thin, with its most recent annual dividend boost totaling 5%. Over the last five years, its dividend has increased by a notable 45%, driving the stock to deliver a total trailing-five-year return for faithful shareholders of 150%. That total return is about double what the S&P 500 delivered in the same time frame.

AbbVie is currently dealing with the fallout from losing patent exclusivity on Humira, which has historically been the world's top-selling drug. While that reality impacted the company's balance sheet, driving revenue and earnings down, this is still a very profitable business. Revenue came in at $14 billion for the third quarter of 2023, while earnings totaled $1.8 billion for the three-month period.

Helping to balance out the decline in Humira revenue was a 52% year-over-year increase in sales of Skyrizi (which treats plaque psoriasis, psoriatic arthritis, and Crohn's disease), and a 60% boost in sales of its drug Rinvoq (indicated to treat multiple ailments including rheumatoid and psoriatic arthritis). Other newer entrants to AbbVie's portfolio, like ​​Vraylar, which is indicated for bipolar 1 disorder or as an add-on for major depressive disorder, and migraine medication Ubrelvy, also provided a helpful boost. Sales of these two products jumped 35% and 46% respectively in the third quarter of 2023 compared to the prior year.

AbbVie is also using its considerable cash stores to fuel a series of acquisitions. It just announced the acquisition of Immunogen in November, which will mark its entry into the commercial market for ovarian cancer treatments, along with the purchase of Cerevel Therapeutics in December, which will add a range of neuroscience assets to its portfolio and pipeline. There's a lot of juice left in this stock yet, and long-term investors who want a steady dividend payer with a robust portfolio of products shouldn't overlook this value stock.