Per os (; P.O.) is an adverbial phrase meaning literally from Latin "through the mouth" or "by mouth". The expression is used in medicine to describe a treatment that is taken<unk> ly (but not used in the mouth such as, for example, caries prophylaxis). The abbreviation P.O. is often used on medical prescriptions.
Oral administration
Subcutaneous infusion
Nasal administration
Subcutaneous injection
Intraperitoneal injection
Intramuscular injection
Intravaginal administration
Transdermal spray