Can the flu cause ear pain and a toothache?

Yes, indeed, your ear pain and toothache may be related to your flu. As Dr Jaclyn, my dental colleague, has rightly described in her answer, this may be due to referred pain where the same group of nerves is supplying surrounding structures because the flu "bug" is causing inflammation and irritation of the lining of your sinuses, teeth and the eardrum.

However, ear pain and fever may also be due to an actual ear infection so it is important to examine the ear carefully to check for any redness, swelling or even infected fluid/pus trapped behind the eardrum.

As the eardrum is an extremely sensitive structure supplied by many nerve branches, an infection here can feel excruciatingly painful. The middle ear (or space behind the eardrum) is directly connected to the back of your nose and throat so "bugs" can easily spread from here to your ear.

In addition to painkillers and anti-inflammatory medications, you might need a course of antibiotics like Augmentin to treat the ear infection. Sometimes, even though the common flu is due to a virus, secondary bacterial infection may develop which needs to be treated with antibiotics before it worsens.

Hope you feel better soon!

Yes, it is possible for sinusitis or a middle ear infection to cause pain in the upper back teeth. This is a phenomenon known as referred pain.

Referred pain occurs when you perceive pain coming from an area that is not diseased. This is due to the sensitization of adjacent nerves. Neurochemical changes that occur as a result of a disease process in the area supplied by one nerve (the sinus) can sensitize another nerve running close by as the nerve branches converge in the brain. The brain then perceives the source of pain to be also located in the structure supplied by the adjacent nerve (the upper back teeth).

If it is indeed referred pain from the inflamed sinus lining that you are experiencing, then the symptoms should stop once the upper respiratory tract infection has cleared up. Your medical GP should be able to sort this out for you.

However, there is the possibility that the pain may be coming from a diseased upper tooth and this is something that your dentist can exclude by examining your teeth and taking xrays to check for infections/abscesses within the bone.

Sinusitis can also be picked up on certain types of dental xrays. I would urge you to see your dentist as soon as possible to make sure that your pain is indeed coming from the sinus and not from an underlying dental infection.