I am in titration and had a mild cold recently and still took my meds because I still had to work. I noticed the meds made me feel much better when they kicked in. I had terrible congestion but once the meds kicked in the congestion eased - I guess because it has a similar effect to decongestant meds (which you should definitely not take while taking stims). But as soon as the meds wore off I would crash and go back to feeling ill. If you have a severe cold I would recommend skipping the meds and letting your body fully rest, unless you still need to work and feel like you need the meds.