Sinus pressure is caused by inflammation or blockage that prevents your sinuses from draining properly. Your sinuses are air-filled cavities behind your forehead, cheekbones, and eyes, each connected to your nasal passages through small openings called ostia. When those openings get blocked by swelling, mucus, or physical obstruction, air and fluid get trapped, creating the painful pressure and fullness you feel in your face. The most common culprits are viral infections, allergies, and structural issues in the nose.
How Blocked Sinuses Create Pressure
Your sinuses have rigid bony walls and depend on tiny drainage openings to exchange air and move mucus out. When those openings are clear, air flows freely in and out, keeping the pressure inside your sinuses equal to the air pressure around you. The system works so smoothly you never notice it.
When something causes the tissue around those openings to swell, the openings narrow or close entirely. Mucus that would normally drain into your nasal passages gets trapped. Air already inside the cavity gets absorbed by the surrounding tissue, creating a vacuum effect (negative pressure) that pulls on the sinus walls and surrounding nerves. That vacuum is what produces the deep, aching sensation behind your cheeks, eyes, or forehead. In other cases, particularly during altitude changes, air can expand inside a blocked sinus and create positive pressure that pushes outward. Either way, the mismatch between the pressure inside the sinus and the pressure outside it is what causes pain.
Viral and Bacterial Infections
The most common cause of sinus pressure is a plain viral upper respiratory infection, what most people call a cold. The virus inflames the lining of your nasal passages and sinuses, causing the tissue to swell and produce excess mucus. That combination blocks the drainage openings and traps fluid inside the cavities. Most viral sinus infections start improving within five to seven days.
Bacterial sinus infections are less common but tend to be more stubborn. They often develop as a secondary problem after a cold has already caused swelling and mucus buildup, creating a warm, stagnant environment where bacteria thrive. The key difference is timing: a bacterial infection typically persists for seven to ten days or longer, and symptoms may actually worsen after an initial period of improvement. Discolored nasal discharge (yellow or green), facial pain, and congestion lasting beyond ten days without improvement are the hallmarks of a bacterial cause. According to the American Academy of Otolaryngology, acute sinusitis is diagnosed when you have cloudy or colored nasal drainage plus either nasal congestion or facial pain and pressure lasting up to four weeks.
Allergies and Histamine
Allergic reactions are another major driver of sinus pressure, especially for people who deal with it seasonally or year-round. When you inhale an allergen like pollen, dust mites, or pet dander, immune cells in your nasal lining release histamine and other inflammatory chemicals. These chemicals make blood vessels in the tissue leak fluid, which causes the lining to swell rapidly. That swelling narrows or blocks your sinus drainage openings in the same way an infection does, trapping mucus and creating pressure.
The difference with allergies is that you typically won’t have a fever, and the discharge tends to be clear and watery rather than thick and discolored. You may also notice itchy eyes, sneezing, and symptoms that follow a pattern tied to specific seasons or environments. Because allergic inflammation can persist for weeks or months if the trigger remains in your environment, it is one of the most common causes of chronic or recurring sinus pressure.
Structural Issues in the Nose
Sometimes the problem is physical rather than inflammatory. A deviated septum, where the wall between your two nasal passages is significantly off-center, can narrow one side enough to impair drainage. Nasal polyps are soft, noncancerous growths that form in the lining of the nose or sinuses. They are painless on their own, but when they grow large enough, they physically block the nasal passages and sinus openings, leading directly to sinus pressure, congestion, and a reduced sense of smell.
These structural causes tend to produce chronic, low-grade sinus pressure rather than the acute episodes you get with a cold. They also make you more vulnerable to infections because mucus can’t drain efficiently, giving bacteria a place to grow. People who get sinus infections repeatedly despite treating them appropriately often have an underlying structural issue contributing to the cycle.
Weather and Altitude Changes
If your sinuses ache when a storm rolls in or when you fly, barometric pressure is the reason. Your sinuses behave like sealed air pockets governed by basic gas physics: when the outside air pressure drops (during a storm, at higher altitude, or during airplane ascent), the air trapped inside your sinuses expands. When outside pressure rises (during descent or clearing weather), the air inside your sinuses contracts.
In healthy sinuses, air moves freely through the drainage openings to equalize the pressure difference, and you feel nothing. But if those openings are even slightly narrowed from mild congestion or allergies, equalization can’t happen fast enough. The expanding or contracting air creates a pressure imbalance that stretches or pulls on the sensitive sinus lining. This is why people with even minor congestion often notice sinus pain during flights, scuba diving, or rapid weather shifts that wouldn’t bother them on a clear, stable day.
Air Pollution and Irritants
Chronic exposure to airborne pollutants can cause sinus pressure even without an infection or allergy. Research from Johns Hopkins found that mice exposed to fine particulate air pollution (particles 2.5 micrometers or smaller, the kind produced by vehicle exhaust and industrial emissions) developed significantly more inflammatory cells in their sinus tissue compared to mice breathing filtered air. The polluted air also caused the protective lining of the sinuses to thicken and weakened the proteins that hold the lining’s cells together, essentially breaking down the barrier that keeps irritants out.
Tobacco smoke, strong chemical fumes, and dry indoor air can produce similar effects. These irritants damage the tiny hair-like structures (cilia) that sweep mucus out of your sinuses. When cilia don’t function well, mucus stagnates, the lining stays inflamed, and pressure builds. This type of chronic irritation helps explain why roughly 11.6% of U.S. adults, nearly 29 million people, have been diagnosed with sinusitis.
When It Might Not Be Your Sinuses
One important thing to know: many headaches that feel like sinus pressure are actually migraines. The American Migraine Foundation notes that a true sinus headache is rare and should involve thick, discolored nasal discharge along with facial pain and pressure. If you have facial pressure with nausea, sensitivity to light, or pain severe enough to disrupt your ability to function at work or home, migraine is a more likely explanation, even if you feel congested.
Migraines can activate the nerve that supplies sensation to the sinuses, producing congestion and a feeling of fullness that closely mimics a sinus problem. The distinction matters because the treatments are completely different. A useful rule of thumb: if your facial pain and pressure don’t resolve within about seven days of your other cold symptoms clearing up, or if your “sinus headaches” keep coming back without obvious nasal symptoms, the cause is likely something other than your sinuses.