PHARMACIES across the country are struggling to process some medication orders after a subsidiary of the second-largest healthcare company in the country was hacked.

UnitedHealth’s technology company Change Healthcare began experiencing problems on Wednesday, according to a filing to the Securities and Exchange Commission submitted the same day.

The company “identified a suspected nation-state associated cyber security threat actor had gained access to some of the Change Healthcare information technology systems,” the filing said.

Change Healthcare reacted to the hack as quickly as possible.

“Immediately upon detection of this outside threat, the Company proactively isolated the impacted systems from other connecting systems in the interest of protecting our partners and patients, to contain, assess and remediate the incident,” the statement said.

However, the security issue was still not resolved on Thursday, resulting in problems processing medication orders at pharmacies across America.

Some customers with insurance offered by UnitedHealth are now struggling to pick up their drug orders, according to Reuters.

CVS pharmacies have had “certain cases” of not being able to process insurance claims since the outage, according to a statement.

“We’re committed to ensuring access to care as we navigate through this interruption,” CVS representatives wrote.

Walgreens pharmacies were also experiencing problems with a “small percentage” of its operations but representatives said that prescriptions were being filled “with minimal delay or interruption.”

Local and regional pharmacies were hit by the cyber attack’s effects too.

“As of this morning, we are still unable to process prescriptions to insurance due to the cyberattack on Change Healthcare,” Knight’s Pharmacy in Berea, Kentucky posted on Facebook Thursday morning.

“Unfortunately this is a national outage and beyond our control.  We hope that the situation will be resolved soon,” the post continued.

“We will be working to fill our backlog of prescriptions as quickly as possible as soon as the system is available. We have not been given an estimated timeframe for restoration of service. Thank you for your patience.”

Change Healthcare was not able to offer a timeline for when the effects of the hack would be eliminated.

“The Company is working diligently to restore those systems and resume normal operations as soon as possible, but cannot estimate the duration or extent of the disruption at this time,” the company’s filing said.

Change Healthcare did not immediately respond to a request for comments.