There are three primary mechanisms through which sinus problems can lead to that unsteady feeling:

Yes, sinus problems can cause lightheadedness . This typically occurs because your sinuses and ears are closely connected; inflammation in one often disrupts the balance systems in the other. 👂 The Sinus-Balance Connection

Your balance is primarily controlled by the in your inner ear. Sinus issues interfere with this system in three main ways:

Fluid and mucus buildup in the sinus cavities can press against the delicate structures of the inner ear, disrupting your equilibrium.

It is vital to distinguish this from inner ear problems (like BPPV or labyrinthitis), which are often misattributed to sinuses.