Hi,
Drainage of clear, slight yellow fluid from nose may be due to infection,
allergy, nasal polyps etc. However, in most of these cases the fluid may become thick after some time due to presence of mucus & immune system cells it can change its color to yellow or green tinge. Most of these symptoms can be treated with OTC drugs. However, a clear liquid drainage from nose, specially from one side of nose may be due to CSF leakage from brain to nose. It may be clear colorless but some times of light yellow color due to presence of degenerated RBC's in CSF.
This leakage may be due to some defect at the base of skull due to any cause of infection, trauma etc. Usually the drainage is more while standing or sitting & becomes less while lying down. The treatment of CSF
rhinorrhea, should be conservative for 7-10 days by complete rest in lying position with head elevation at 15-30 degree, if the leakage is spontaneous or intermittent. If the symptoms don't resolve, then a further diagnosis by imaging etc., will be required and treatment will have to be done accordingly.
Take care. Hope I have answered your question. Let me know if I can assist you further.
Regards,
Dr. Satnarain Bansal, General & Family Physician