Face swelling has dozens of possible causes, ranging from a salty meal the night before to a serious allergic reaction that needs emergency treatment. The location, speed of onset, and accompanying symptoms usually point toward the reason. Here’s a breakdown of the most common and most important causes.
Allergic Reactions
Allergies are one of the most frequent reasons for sudden facial swelling. Mild reactions to pollen, pet dander, or certain foods can cause puffiness around the eyes and lips. A more significant form called angioedema produces painless swelling deeper under the skin, typically affecting the eyes, lips, and tongue.
The most dangerous allergic reaction is anaphylaxis, which can cause the throat and tongue to swell enough to block your airway. Symptoms usually appear within minutes of exposure to a trigger, though they can sometimes be delayed by 30 minutes or more. Other signs include hives, a rapid and weak pulse, difficulty breathing, dizziness, and a drop in blood pressure. Anaphylaxis requires an epinephrine injection immediately. If you or someone near you shows these symptoms, use an epinephrine autoinjector if available and call emergency services, even if symptoms seem to improve after the injection.
Infections
Several types of infection cause the face to swell, often on one side. Sinusitis is among the most common, producing swelling and tenderness around the cheeks, eyes, or forehead along with congestion and pressure. Cellulitis, a bacterial skin infection, causes a spreading area of redness, warmth, and swelling that can worsen quickly without antibiotics. Pink eye can make the tissue around one or both eyes look puffy.
Swollen lymph nodes in the neck from a viral or bacterial illness can also make the lower face and jaw area look fuller than usual.
Dental Problems
A tooth abscess is an underappreciated cause of facial swelling. When bacteria infect the tissue around a tooth root, pus builds up and the infection can spread into the surrounding jaw and cheek. Symptoms include intense toothache, redness inside or outside the mouth, sensitivity to hot and cold, a bad taste, difficulty opening your mouth, and sometimes a fever with swollen neck glands.
Most dental abscesses develop gradually, giving you time to see a dentist. But if swelling makes it hard to breathe, swallow, speak, or open your mouth, or if it spreads near your eye or affects your vision, that’s an emergency. Untreated dental infections can spread to deeper tissues in the head and neck.
Medications
Certain drugs cause facial swelling as a side effect. The most well-known culprits are ACE inhibitors, a class of blood pressure medication. These drugs cause angioedema in roughly 0.1 to 0.7 percent of people who take them, and the risk is up to five times higher in people of African descent. ACE inhibitors are the leading cause of drug-induced angioedema in the United States, responsible for 20 to 40 percent of all emergency department visits for angioedema each year.
The tricky part is that this reaction can happen at any point during treatment, not just when you first start the medication. Corticosteroids, some anti-inflammatory drugs, and other medications can also trigger facial puffiness through different mechanisms. If you notice new swelling after starting or changing a medication, it’s worth flagging to your prescriber.
Kidney Disease
When your kidneys aren’t filtering blood properly, protein leaks into the urine and fluid builds up in places it shouldn’t. This condition, called nephrotic syndrome, commonly causes swelling in the face and around the eyes, especially in the morning. It happens because low protein levels in the blood allow fluid to seep out of blood vessels and collect in soft tissue.
Facial puffiness from kidney problems tends to be worst upon waking and may improve as the day goes on and gravity pulls fluid downward. It’s often accompanied by swelling in the ankles and feet, foamy urine, and fatigue. If you notice persistent puffiness around your eyes that doesn’t have an obvious explanation, kidney function is one of the things worth checking.
Thyroid Disorders
Both an overactive and an underactive thyroid can change how your face looks. Hyperthyroidism, where the thyroid produces too much hormone, is listed among the conditions that cause facial edema.
Severe hypothyroidism produces a distinctive type of swelling called myxedema, where the skin and soft tissues thicken with a jelly-like substance. The classic appearance includes generalized facial puffiness, swelling around the eyes, a swollen tongue, drooping eyelids, and coarse, thinning hair. This develops slowly over months or years, so people often don’t notice the changes until they compare old photos or someone else points it out.
Other Hormonal and Systemic Causes
Cushing syndrome, caused by prolonged excess cortisol (whether from a medical condition or long-term steroid use), produces a characteristic rounding of the face sometimes called “moon face.” Lupus, an autoimmune disease, causes inflammation that can affect the skin and soft tissues of the face along with joints and organs. Preeclampsia, a pregnancy complication involving high blood pressure, frequently shows up as sudden facial swelling, particularly after the 20th week of pregnancy.
Injury and Trauma
A blow to the face from a fall, sports injury, or accident causes swelling as blood and fluid rush to the damaged area. This includes broken noses, fractured jaws, and soft tissue bruising. Swelling from facial trauma typically peaks within the first day or two and takes 5 to 7 days to go down substantially. Applying a cold compress in 15- to 20-minute intervals during the first 48 hours and keeping your head elevated, even while sleeping, helps limit how much fluid accumulates.
Swelling on One Side Only
When swelling appears on just one side of the face, the list of likely causes narrows. Salivary gland problems are a common one: a blocked salivary duct (from a small stone) or an infected salivary gland causes swelling near the jaw or below the ear that often worsens around mealtimes. Cysts, which are fluid-filled lumps under the skin, and lipomas, noncancerous fatty growths, can also produce a visible lump or asymmetry. A dental abscess almost always swells on the side of the affected tooth.
Diet, Alcohol, and Sleep
Not all facial swelling signals a medical problem. A high-sodium meal causes your body to hold onto extra water to balance out the salt, and that retained fluid often shows up in the face. This is especially noticeable in the morning because lying flat overnight lets fluid distribute more evenly rather than pooling in your legs. Alcohol has a similar effect by promoting dehydration and triggering an inflammatory response. Poor or insufficient sleep, crying, and even sleeping face-down can leave you looking puffy.
This type of swelling is temporary and resolves on its own, usually within a few hours of being upright and hydrated. Reducing sodium intake is the most reliable way to prevent it, though there’s no magic threshold. The more salt you eat, the more water your body retains.
How to Tell What’s Serious
The speed of onset matters most. Swelling that develops over seconds to minutes, especially with breathing difficulty, hives, or lightheadedness, suggests anaphylaxis or severe angioedema. Swelling that worsens over hours alongside fever, spreading redness, or increasing pain points to an active infection. Gradual, persistent puffiness over weeks or months without an obvious trigger may reflect a kidney, thyroid, or hormonal issue worth investigating with blood and urine tests.
Swelling that’s clearly linked to something you ate, drank, or did the night before and resolves by midday is almost always benign. Swelling that keeps coming back without explanation, affects your breathing or vision, or comes with other new symptoms is the kind that deserves a closer look.