People going to Royal Cornwall Hospital's A and E with minor injuries and ailments will be redirected to alternative services until after the New Year.
The change comes amid growing pressure on Truro's Emergency Department.
Susan Bracefield, the Director of Operations at the hospital trust, said: "We need our clinical teams to be able to focus on those who really need their specialist skills, so we’ve taken the decision to redirect patients to alternative services during the minor injury unit opening hours."
She added: "It’s vital that we maintain a safe service for everyone and there are a lot of people who come to us who can easily be seen and treated elsewhere."
People are being advised to travel to other minor injury units across Cornwall for the following conditions:
- Sprains and strains
- Broken bones
- Minor burns and scalds
- Head injuries (unless the injured person is unconscious)
- Insect and animal bites and stings
- Minor eye injuries
- Bruising and grazes
Those who aren't sure if their injury is minor is advised to telephone their local unit before setting out to call NHS 111.
Cornwall's other minor injuries units which will be available are:
- Bodmin Community Hospital - open until 10 pm
- Camborne and Redruth Community Hospital - open until 10pm
- Falmouth Community Hospital - open until 8pm
- Helston Community Hospital - open until 8pm
- Launceston Community Hospital - open until 8pm
- Liskeard Community Hospital - open until 10pm
- Newquay Community Hospital - open until 10pm
- St Austell Community Hospital - open until 8pm
- St Mary's Community Hospital, Isles of Scilly - open 24 hours
- Stratton Community Hospital - open until 10pm
- Stennack Surgery, St Ives - open until 8pm