Cold sores - will fluocinonide treat a cold sore?

No. Fluocinonide is a potent topical steroid cream. It will not help.
It is recommended not to use a topical steroids on a cold sore. Topical steroids can cause the cold sore to spread making it more difficult to treat.

There are several medications to reduce the duration or symptoms of cold sores.
Using topical anesthetics such as benzocaine or lidocaine will help relieve burning, itching, and pain.
Treatment with topical antivirals such as acyclovir (Zovirax 5% cream) or penciclovir (Denavir 1% cream) will reduce healing time and pain - but are prescription medicines.
If you get cold sores frequently you may need to take an oral antiviral continually.
See your pharmacist or doctor for more advice.