Hi practo user, Thanks for your message. I'm not quite sure on what context ( asthma, allergy, respiratory illness) you have been adviced by your physician that not to have citrus after 6 pm. To my knowledge, I haven't come across this citrus and after 6 connection till now. I'm sure lemon rice, salad dressing should be absolutely fine to consume. Vitamin C supplement can be consumed during any part of the day. It is always better to optimise through your dietary intake, incase if you are not able to or find it challenging, then you can opt for vitamin C supplements. Vitamin C actually helps to build your immunity and it's a common myth to avoid vitamin C. But it is recommend to clarify with your doctor about why he has suggested to avoid vitamin C. Hope this answer helps!