How does anti-viral drug (such as valacyclovir HCL) actually work in the body? How may it hurt the body? (I mean, obviously healthy people don t take valacyclovir HCL to improve their immunity/health). I ask this because, after taking 5 days of this medicine, I am wondering if I should take the other 2 days of supply or I should stop taking the medicine. Originally the nurse practicianer only prescribed 5 days of supply of the medicine for me for shingles. Only after I expressed concern that it might not be sufficient did she increase it to 7 days. Now I have finished 5 days of valacyclovir and the shingles is healing up (but not completely healed). I started taking the medicine after 3 days of outbreak of shingles on my face/neck.