This piece has some very small pin holing on the inside which is generally thought to be able to hold onto bacteria, and could be harmful.  Some potters care a great deal about this, and some don’t. I personally don’t worry about it with the mugs and cups I use at home, and have never heard of a verifiable case of someone getting sick from this, however, I’ve discounted it nonetheless, and it is up to you if you want to use it to drink from, or find another use for it. The pinholes are pictured.

Thrown on the wheel in an earthy red clay, then decorated by hand with white terra sigillata, oxides and underglazes to create semi-abstract, moody landscapes.

Fired to cone 5 in an electric kiln.

Microwave safe, however I don’t recommend putting in the dishwasher.