A maternity nurse tells a pregnant woman that she can use her WeChat to consult doctors about her physical conditions. [Photo provided to China Daily]

Social media heavyweight Tencent has also moved into the sector. So far this year, it has signed partnership deals with medical instrument manufacturers Guangdong Biolight Meditech Co Ltd in China and Scanadu, a Silicon Valley-based medical devices maker in the United States.

This comes at a time when the online healthcare market is poised for huge growth.

A report by Analysys International showed the industry was worth 11.4 billion yuan ($1.79 billion) last year, an increase of 22.6 percent compared to the same period in 2013.

Overall, the healthcare sector in China was worth 2.63 trillion yuan ($413 billion) in 2014, according to data from Deloitte Touche Tohmatsu Ltd.

"With an aging population and increasing public awareness on fitness and health, more people will rely on online and mobile platforms to enjoy medical services," Lin, of Analysys International, said. "The market will grow into an industry of 36.5 billion yuan in 2017."

But there are challenges ahead as the healthcare industry is controlled and funded by government organizations.

Indeed, prescription drugs can not be sold on Alibaba's e-commerce site Tmall, even though it already deals in over-the-counter medicines. "Only when the government greenlights more medical businesses to private players, will the online health market really boom," Qin Zexi, an analyst at research firm iResearch Consulting Group, said.

Still, Alibaba, Tencent and Baidu are making significant progress. Patients can now use online platforms, such as Alibaba's Alipay and Tencent's WeChat, to consult doctors, make appointments, pay bills and check medical reports. In the past few years, medical delivery service apps have also mushroomed.

In the near future, "telediagnosis" is another area the Internet big three will probably move into. This is a process whereby a disease diagnosis, or prognosis, is made by the electronic transmission of data between distant medical centers. Technology will play a key role in this.

"The Internet trio are spending heavily in the sector, but currently most of their services don't touch upon the key aspect of telediagnosis," Qin said. "As more public hospitals embrace online technology and Internet companies, telediagnosis will become a growing trend."

For now, Internet companies are carving out niche roles in the healthcare industry.

Baidu is concentrating on big data technology, a broad term for processing vast amounts of complex statistics, which can be boiled down into market trends. Around 26 million people search for medical information on its platform, according to the company.