Dreadful, especially in older people, as you may have heard

I am copying the following treatment from a special book about essential [etheric] oils [ Schnaubelt Ph.D., Kur , see below]

To my SHAME I never used this before but will advise this now if necessary!

A blend of Ravintsara (Cinnamomum camphora) and Foraha (Calophyllum inophyllum) has become the standard treatment option for shingles outbreaks. Especially with elderly patients this treatment almost invariably offers stunning relief from the excruciating pain and brings renewed quality of life. After the initial treatment, frequency and severity of subsequent outbreaks is often reduced drastically.
The classic formula for shingles treatment calls for equal parts of Ravintsara and Calophyllum inophyllum. This blend is applied directly onto the lesions. This can be done with a Q-tip or simply by dabbing a few drops onto the lesion with the finger. This is repeated frequently at the beginning of the treatment. (Doing this 4 or 5 times on the first day of treatment is fine.)

Schnaubelt Ph.D., Kurt. The Healing Intelligence of Essential Oils: The Science of Advanced Aromatherapy (Kindle Locations 3413-3417). Inner Traditions/Bear & Company. Kindle Edition.