Healthcare software giant Epic Systems was hit with a lawsuit on Monday by a startup accusing it of unlawfully controlling the market for U.S. medical records, harming patient care and causing health plans to pay higher costs.

Particle Health has alleged Epic is a “monopolist” in the electronic health data market. But experts say it's a hard case to win.

Health data startup Particle Health sued electronic health records giant Epic Systems for federal antitrust violations on Monday, charging it uses its control over troves of patient records to stifle competition.

Particle Health, a startup that helps providers and health technology companies aggregate and share data, filed a suit Monday in the U.S. District Court for the Southern District of New York alleging Epic is using its market power to prevent products that would compete with the EHR company's payer platform .