Should I continue using my acne cream or stop after 1 tube?

Yes, you should continue using your acne cream for several weeks to see good results. Since you have a large area to cover, it is normal to need a lot of cream. If you are concerned about being asked questions by the pharmacist, you can explain to the technician that you need to renew the tube after only one week because you have a large area to treat. This way, they can make a note in your file and no one will question you. Don't be embarrassed, pharmacists just want to help you.