Why Teeth Hurt After the Flu: Maxillary Sinus Pressure vs. Referred Trigeminal Nerve Pain

If your teeth hurt after flu, the discomfort may not be coming from the teeth themselves. Influenza and other respiratory infections can cause inflammation, congestion, coughing, dehydration, and facial pressure. These symptoms may make the upper teeth feel sore or sensitive.

However, tooth pain after an illness can also be caused by a dental problem, such as decay, a cracked tooth, gum infection, or inflammation of the tooth’s pulp. Less commonly, pain may be “referred” through the trigeminal nerve—the main sensory nerve of the face—so it feels as though a tooth hurts even when the tooth is healthy.

The pattern of pain, its location, and what triggers it can provide useful clues.

How maxillary sinus pressure can make teeth hurt

The maxillary sinuses are air-filled spaces located behind the cheekbones and directly above the roots of many upper back teeth. When a viral infection causes nasal and sinus lining inflammation, mucus may not drain normally. Pressure and swelling in the maxillary sinuses can then irritate nearby branches of the trigeminal nerve.

Because the sinus and upper teeth share nearby nerve pathways, the brain may interpret sinus pressure as tooth pain. This is called referred pain.

Sinus-related tooth discomfort often has these features:

• An ache or pressure in several upper teeth, usually on one side or both sides
• Pain in the upper back teeth rather than a single clearly affected tooth
• A feeling of fullness or pressure in the cheek, under the eye, or forehead
• Nasal congestion, reduced sense of smell, or thick nasal drainage
• Pain that becomes worse when bending forward, coughing, or moving the head
• Tenderness when pressing over the cheek or sinus area
• Symptoms that improve as the congestion and facial pressure improve

A viral infection can inflame the sinuses even when it is not technically bacterial sinusitis. Most sinus infections caused by viruses improve without antibiotics. Antibiotics do not treat influenza or other viruses, and they are not routinely useful for uncomplicated viral sinus symptoms.

Could the pain be from the trigeminal nerve?

The trigeminal nerve carries sensation from the face, teeth, gums, sinuses, and jaw. This overlapping nerve supply explains why pain can sometimes be difficult to locate. The source may be a sinus, tooth, jaw muscle, or nerve, but the brain may identify the pain as coming from a different nearby structure.

A respiratory infection may irritate facial nerve pathways indirectly through inflammation, sinus pressure, coughing, or muscle tension. Some people also develop nerve sensitivity after an infection. Still, classic trigeminal neuralgia is uncommon and has a distinctive pattern.

Trigeminal nerve pain is more likely to feel like:

• Sudden, severe, electric-shock-like or stabbing pain
• Brief attacks lasting seconds to a couple of minutes
• Pain limited to one side of the face
• Episodes triggered by touching the face, brushing the teeth, chewing, speaking, shaving, or a cool breeze
• Pain that occurs in bursts, with relatively normal periods between attacks

This pattern is different from the steady pressure or aching commonly associated with sinus inflammation. Trigeminal neuralgia should not be diagnosed based on symptoms alone. A doctor or dentist may need to examine you and rule out dental, sinus, jaw, and other causes.

Signs that the tooth itself may be the problem

A tooth can hurt after the flu simply because a dental problem happened to become noticeable at the same time. Illness may make existing pain more obvious, especially if you are dehydrated, clenching your jaw, eating differently, or not maintaining your usual oral-care routine.

A dental cause is more likely when:

• One tooth is clearly painful rather than several upper teeth
• Pain is triggered by hot, cold, sweet, or acidic foods
• Pain continues after the trigger is removed
• Biting or chewing causes sharp pain
• The tooth feels high or tender when you close your mouth
• There is swelling around the gum, a bad taste, or drainage
• Pain is severe at night or wakes you from sleep
• Symptoms continue after your nasal congestion and facial pressure have resolved

A cavity, cracked tooth, inflamed pulp, gum infection, or dental abscess can worsen without treatment. Pain medication may temporarily reduce symptoms but will not repair the underlying tooth.

Lower-tooth pain is generally less likely to come from the maxillary sinuses. If a lower tooth hurts, or if one specific tooth is consistently sensitive, arrange a dental examination rather than assuming the flu is responsible.

How a clinician distinguishes the causes

A dentist may tap or apply pressure to individual teeth, test their response to temperature, examine the gums, and take dental X-rays if needed. A doctor may assess your nose, throat, face, ears, lymph nodes, and breathing, and ask how long your symptoms have lasted.

The timing matters:

• Symptoms beginning during a respiratory infection and improving with congestion are more consistent with sinus-related referred pain.
• Pain that remains after the respiratory illness improves deserves a dental or medical evaluation.
• Symptoms that last more than about 10 days without improvement, become significantly worse after initially improving, or include persistent fever may indicate a bacterial complication or another condition that needs assessment.
• Repeated attacks of brief, shock-like facial pain may require evaluation for nerve-related pain.

A free, online symptom check, using the doctor approved Ubie Symptom Checker, may help you organize your symptoms and decide what type of care to seek. It does not replace an examination or diagnosis by a qualified professional.

What you can do at home

If your symptoms are mild and improving, supportive care may help:

• Drink enough fluids unless a clinician has told you to restrict them.
• Use saline nasal spray or a saline rinse made with properly distilled, sterile, or previously boiled and cooled water.
• Rest and avoid cigarette smoke and other airway irritants.
• Apply a warm, damp cloth to the cheek or face.
• Use acetaminophen or ibuprofen only if they are safe for you and follow the package directions. Avoid exceeding the recommended dose.
• Continue gentle brushing and flossing.
• Avoid placing aspirin directly on a tooth or gum, because it can damage the tissue.
• Ask a pharmacist or doctor before using decongestants, especially if you have high blood pressure, heart disease, glaucoma, prostate problems, are pregnant, or take other medicines.

Do not start leftover antibiotics. A clinician should decide whether antibiotics are appropriate.

When to see a dentist or doctor

Make a dental appointment if pain is focused in one tooth, is triggered by temperature or chewing, lasts more than a day or two, or continues after your flu and congestion have improved. You should also seek care for gum swelling, facial swelling, pus, a persistent bad taste, or difficulty opening your mouth.

Speak to a doctor about symptoms that could be serious or life-threatening. Seek urgent medical care for:

• Trouble breathing or swallowing
• Swelling of the face, mouth, tongue, or throat
• Swelling around the eye, vision changes, or severe eye pain
• A severe headache with stiff neck, confusion, fainting, or unusual drowsiness
• High or persistent fever, or rapidly worsening illness
• Severe dehydration, chest pain, or blue or gray lips
• New weakness, numbness, or difficulty speaking

Most cases of teeth hurt after flu are caused by temporary sinus pressure or an unrelated but treatable dental problem. The key distinction is whether the pain affects several upper teeth along with congestion and facial pressure, or whether one tooth has its own clear sensitivity, chewing pain, or swelling. When the pattern is unclear—or the pain is severe or persistent—a dentist or doctor can identify the source and recommend the right treatment.