Impotence is a known side effect of Propecia. Taking Viagra may help if you continue to need Propecia.
In general, Propecia is a pretty safe medication for baldness.
If the Propecia is not the cause of the ED, checking a testosterone level as well as examining blood flow to the penis can be considered. Blood tests to evaluate for metabolic diseases like thyroid disorders or diabetes can be considered.
Followup with your personal physician is essential.
This answer is not intended as and does not substitute for medical advice - the information presented is for patient education only. Please see your personal physician for further evaluation of your individual case.
Kevin, M.D.
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