Apologies if the answer to this is in a thread somewhere. I have been on 2.5 mg for a month and lost a stone. I switched suppliers to MedExpress, who would only prescribe 2.5 mg for a new customer. I am finding in week 5 that it isn't working very well any more and I probably need to go up to 5 mg. Can I take two doses of the 2.5 mg from the 2.5 mg pen? I don't see why not, but there might be some reason !