Hospital patients in Guernsey will now only be able to have one visitor per day.
It follows a rise in coronavirus cases, which has led to a shortage of beds and some elective surgeries and outpatient appointments having to be postponed.
Hospital director Dr Peter Rabey said it was "very busy at the moment" and hopes the measures will "reduce the potential spread of the virus".
Visitors must be symptom-free and have had a negative lateral flow test beforehand.
In addition, only one birth partner will be allowed in the hospital and two main caregivers for any paediatric admission.
There are currently nine patients at the Princess Elizabeth Hospital with Covid-19 and "very few spare beds in Intensive Care Ward."
Dr Rabey added: "We are seeing a rise in cases within nursing and residential homes which causes a knock-on effect with our ability to transfer patients."
He added that the restrictions would be kept under "regular review" and removed "as soon as possible".