hello and welcome to HCM forum,
i would like to inform you that tadalafil
is available in 2.5,5,10 and 20mg dosage.
according to the medical condition, dosage is decided. 20mg is a high dose and it should be taken once in every 36 hours , as and when needed, if over dosage occurs it may cause hypotension
i hope i answered you query.
i wish you good health.