Toothache or allergy/sinus flare up, what's the difference?

They both hurt: ..But if the source of the trouble is dental in origin, you will need to see a dentist for evaluation and treatment. If the origin is sinus, it will feel like a toothache but not really have a dental solution. Differentiating these can be tricky and often the key is do you have multiple teeth feeling uncomfortable or a recent cold? See your dentist and share all your observations.

Either: Toothache is not expected in allergic rhinitis or sinusitis. On very rarely occasions, the tooth may be infected if the infection in the maxillary sinus erodes the bony floor of the sinus and gets into the root of the tooth. Toothache will not get better if the tooth is decaying and may often throb. Throbbing is also not expected with any ache associated with nasal or sinus issues.

Causation: A toothache (upper molar) can occur with sinus infection. Treat sinusitis. If dental pain persists, see DDS. Alternativly, tooth infection can cause sinus infection.