How fast does acyclovir start working?
Acyclovir works by stopping viral DNA replication, so you generally see effects as the medicine gets the virus under control. For common uses like cold sores (herpes labialis) or genital herpes (herpes simplex), acyclovir typically starts working quickly after you take it, but the most noticeable improvement often takes a little time.
How soon will symptoms improve for cold sores?
With cold sores, people usually notice that new sores stop getting worse within about a day after starting treatment, especially if they begin early (at the first signs like tingling or burning). Healing and crusting then take several more days.
How soon will it help with genital herpes?
For genital herpes, starting acyclovir early in an outbreak can shorten how long symptoms last. Many people see improvement over the first 1–3 days, with continued improvement over the next several days as lesions heal.
Does timing (starting at the first sign) change how soon it works?
Yes. Antiviral drugs like acyclovir work best when you start them early in the course of symptoms. If you wait until lesions are fully developed, the medicine may still help, but symptom improvement usually isn’t as fast or as strong.
Which formulation matters (pills vs cream)?
Acyclovir can be used as:
- tablets (systemic treatment),
- creams/ointments (topical).
In practice, pills often reduce viral shedding and can lead to faster overall symptom improvement for outbreaks, while topical treatment may mainly help at the surface level and may take longer to see full results.
What if acyclovir doesn’t seem to be working?
If symptoms are not improving after a couple of days on treatment, or if outbreaks are severe (for example, extensive sores, fever, or trouble urinating), contact a clinician. They may need to confirm the diagnosis, adjust the dose, or consider other causes (such as non-herpetic sores).
Are there emergency situations?
Get urgent care if you have eye pain/redness, vision changes, a weakened immune system, or widespread infection symptoms—these can require prompt evaluation and different management.
Sources
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