Hello,
Medications such as blood pressure medications (especially beta-blockers), heart medications (such as digoxin), some peptic ulcer medications, sleeping pills, and antidepressants may also cause erectile dysfunction. Erectile dysfunction is not a reported side effect of Valtrex.
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.
I'm sure it is from the medication. Tell him he needs to tell his doctor about this.
♡Princess