Originally Posted by
panic_down_under
Light-headedness is a common side-effect of many psych meds, but it is also an anxiety symptoms so it can be difficult to determine which is responsible, but if this wasn't an issue pre treatment then mirtazapine is the most likely culprit.
Mirtazapine is a very potent antihistamine, more potent than most of the meds sold as antihistamines, and one of the side-effects can be a drying out of the mucus membranes and I suspect this is what is causing the sinus problems. Do you also have dry-mouth? Sinusitis is a listed side-effect, although an uncommon one, as is otitis media, aka ear infection, caused by blockage of the eustachian tubes connecting the middle ear to the back of the nose and throat which facilitates infection.
The antihistamine effect is strongest at low doses. It usually lessens as the dose increases to those typically prescribed for anxiety and depression - 30-45mg. Increasing your fluid intake may help.