The drainage is probably from a condition called "vasomotor rhinitis (VMR)". This is common in people with vascular problems, as it is a vascular problem in the lining of the nose and sinuses. When there is increased blood flow, there is increased drainage. Most likely, this is coming from your sinuses and therefore drains down the back of your throat and not out of your nose. A couple of things might help. First get a CT scan of the sinuses to be sure there is no infection. Next, I would suggest a trial of oral steroids for a short period of time. If this is VMR, it will go away for a while, but unfortunately come back. At least it will explain the problem. If it is VMR, increasing the inhaled nasal steroids sometimes helps a little, but there is no way to eliminate the problem as long as the basic condition persists, in your case lupus.
hi - i have had bad post nasal drip for many years. Docs have assumed it's a reaction to airborn allergens ie pollen. Antihistamines and steroid sprays have not really helped. Some layman suggested knocking out wheat from my diet and it has worked. I can exercise and breathe normally after years. It's right in the pollen season here now and I've been off any medications for a couple of months. I have noticed a very mild amount of pollen reaction (slightly itchy eyes etc) but the post nasal drip has gone. What made it worse was loading up on a wheat based breakfast in the morning and pasta dinners. Knocking those out made a hughe difference. Then since getting off white bread, biscuits, etc it's resolved completely. I have noticed I can tolerate a certain amount of wheat food now - like the sensitivity has relaxed - but it seems to come back if I eat too much. So I'm happy to each wheat free bread etc - it's not hard to do and retain a decent balanced diet. I never through I could feel so healthy again - at one point I could hardly walk 50 metres without real breathing problems from rediculous amounts of mucous - I'd be coughing it up all day long. The doctors don't seem to believe that this is the cause - but the approach they've used failed.