Bringing medication to Vietnam

I am coming to Vietnam from the UK. I take an anti depressant - Sertraline. The government guidance says that I can only bring 10 days worth of these with me as they are viewed as a psychotropic. I will be in Vietnam for 21 days. I'll have a letter from the doctors and a copy of the prescription. Am I likely to have any issues with this? I'm only bringing hand luggage.