How fast does Famvir (famciclovir) start working?
Famvir (famciclovir) usually starts working within about a day of taking it for viral infections. Many people notice that symptoms begin to improve within 24 hours, though the exact timing depends on what you’re treating and how quickly you start the medicine after symptoms begin.
How long until symptoms improve for shingles vs. cold sores?
Treatment timing matters. Starting Famvir early (as soon as you notice symptoms) generally leads to faster symptom improvement:
- For shingles, pain and other symptoms often start easing within the first day or two, with more noticeable improvement over several days.
- For cold sores, healing and reduced symptoms typically progress over a few days, but full healing still takes time even after the medicine has started working.
Does the dose or timing change how quickly it works?
Yes. How quickly it helps can vary with:
- When you start treatment (earlier is usually better)
- The prescribed dosing schedule
- Whether the infection is mild vs. more severe
When should you contact a clinician if it isn’t working?
If symptoms aren’t improving after a couple of days, or if they worsen at any point, you should contact your prescriber. That’s especially important for shingles or if you’re immunocompromised, because delays can affect outcomes.
Source
No sources were provided with your question, and there isn’t enough supplied information here to cite official timelines for Famvir’s onset of action.