Yes, a sinus infection (sinusitis) can cause a toothache. In fact, pain in the upper back teeth is a fairly common symptom with sinus conditions.

The sinuses are pairs of empty spaces in your skull connected to the nasal cavity. If you have sinusitis, the tissues in those spaces become inflamed, often causing pain.

The largest sinuses are a pair above the back teeth of your upper jaw. The roots of the upper teeth are very near or may even extend into the sinus cavity. Consequently, inflammation in the sinuses might cause pain in nearby teeth. Similarly, damage to or infection in a tooth may lead to persistent (chronic) sinusitis.

If you have a toothache, first consult your dentist for an exam. He or she will look for possible dental causes for the toothache, such as gum disease, cavities or other infections.

If your dentist rules out a dental cause for the toothache, consult your doctor. He or she will consider whether a sinus condition or another medical problem is causing pain.