Sinus Infection: Symptoms, Causes, Care & Red Flags

Introduction

A stuffy nose, facial pressure, and thick mucus may point to a sinus infection [1,6]. This condition is also called sinusitis [1].

Sinusitis starts when the lining of one or more sinuses becomes swollen [1,2]. The swelling can block normal mucus flow and cause fluid to build up [1,5].

Most acute sinus infections start with a virus, such as a common cold [3,5]. They often improve within seven to 10 days without antibiotics [5,7].

This guide explains sinus infection symptoms, causes, treatment and when to see a doctor. It also covers home care and key sinus infection warning signs.

Overview: What Is a Sinus Infection?

The sinuses are hollow spaces in the bones of the face [2,8]. They sit near the nose, cheeks, forehead, and eyes [2,8].

The sinus lining makes mucus [8,10]. This mucus traps germs and other small particles [8]. Tiny hairs called cilia move mucus through small openings into the nose [8].

Sinusitis means the sinus lining is inflamed or swollen [2,6]. An infection can cause this swelling, but allergies and other problems can also cause it [2,6].

How inflamed and blocked sinuses cause symptoms

Swelling can narrow the small openings that drain the sinuses [8,10]. Mucus may then become thick and collect inside them [5,8].

This buildup can cause pressure, pain, congestion, and nasal drainage [5,8]. Trapped fluid may also allow germs to grow [1].

Blocked sinuses do not always mean bacteria are present [2,6]. Viruses and allergies can also cause swelling and poor drainage [3,6].

Sinus pressure may affect the forehead, cheeks, nose, or eye area [5,7]. Swelling and mucus can also make nose breathing hard [5].

Acute, subacute, and chronic sinusitis

Healthcare professionals group sinusitis by how long it lasts:

• Acute sinusitis lasts up to four weeks [2,6].
• Subacute sinusitis lasts four to 12 weeks [2].
• Chronic sinusitis lasts more than 12 weeks [2,5].

Acute sinusitis often follows a viral upper airway infection [3,5]. The common cold is a frequent cause [5].

Long-term or repeated symptoms may need more checks [1,2]. Allergies, growths, or a blocked nasal passage may play a role [1,6].

How sinusitis differs from a common cold

Colds and acute sinusitis can cause many of the same symptoms [1,3]. Both can cause congestion, drainage, headache, cough, and tiredness [1,7].

In fact, a cold is the usual cause of acute sinusitis [5]. Most viral cases start to improve within seven to 10 days [5,7].

A different pattern may point to acute bacterial rhinosinusitis [1,5,7]. Rhinosinusitis means swelling in both the nose and sinuses.

Possible signs include symptoms that last more than 10 days without improvement [1,7]. Severe symptoms or new decline after improvement are also key clues [1,5].

Mucus color alone cannot show whether bacteria caused the illness. A clinician looks at the full pattern and length of symptoms [1,3].

Symptoms of a Sinus Infection

Sinusitis symptoms can differ from person to person [5,6]. The affected sinus and amount of swelling can shape the symptoms [5,6].

Nasal blockage, drainage, and facial discomfort are common sinusitis symptoms [1,6]. Some people also have symptoms in the throat, ears, or upper teeth [1,7].

Nasal, facial, and breathing symptoms

Common sinus infection symptoms include:

• A stuffy or blocked nose [1,7]
• A runny nose [1,6]
• Thick, cloudy, or colored mucus [6,7]
• Mucus dripping down the throat [1]
• Facial pain, pressure, or fullness [1,7]
• Headache [1,5]
• Trouble breathing through the nose [5]
• Less sense of smell or taste [7]

Mucus that flows down the throat is called postnasal drip [1]. It may irritate the throat and lead to coughing [1].

Facial pressure may affect the forehead, cheeks, nose, or eye area [5,7]. The pain may throb or feel like fullness [5,7].

Congestion can make the face feel swollen or sore [4,5]. Pain may become more clear when mucus cannot leave the sinuses [5,8].

Other symptoms that may occur

A sinus infection can cause symptoms outside the nose and face [1,7]. These may include:

• Cough [1]
• Sore throat [1]
• Bad breath [1,7]
• Tiredness [7]
• Fever [6,7]
• Ear pain or pressure [7]
• Upper tooth pain [7]

Not every person has every symptom. A viral case can still cause strong discomfort without a bacterial infection [3,5].

Fever may occur with acute sinusitis [6,7]. However, one symptom alone does not prove that bacteria are present [1,3].

Clues symptoms may be bacterial or chronic

Most acute sinus infections come from viruses [3,5]. Bacteria cause a smaller share of acute cases [3,6].

Symptoms lasting more than 10 days without improvement may suggest acute bacterial rhinosinusitis [1,7]. Severe symptoms can also suggest a bacterial cause [1].

Some people improve and then get worse again [1,5]. This pattern may also point to acute bacterial rhinosinusitis [1,5,7].

Most acute viral cases improve within seven to 10 days without antibiotics [3,5,7]. Antibiotics do not treat the viruses behind most acute cases [1,3].

Symptoms lasting over 12 weeks meet the time-based definition of chronic sinusitis [2,5]. Repeated episodes may relate to allergies or a physical blockage [1,6].

Causes and Risk Factors

Viruses, bacteria, fungi, allergies, and blocked drainage can cause sinusitis [3,6]. Viruses are the most common cause of acute sinusitis [3].

The cause matters because many cases do not need antibiotics [1,3]. A clinician can assess whether bacteria are likely [1].

Viral, bacterial, fungal, and allergy-related causes

Acute sinusitis often starts during or after a cold [5,7]. A virus can cause swelling that makes sinus drainage harder [5,10].

A bacterial sinus infection may begin after drainage becomes blocked [8,10]. Bacteria can multiply in fluid trapped inside the sinuses [8,10].

Still, most acute sinus infections are not bacterial [1,3]. Many improve without antibiotic treatment [1,5].

Fungi can also cause sinusitis [3,6]. However, viruses are the most common cause of acute disease [3].

Allergies can inflame tissues in the nose and sinuses [6,10]. This swelling can block drainage even when no infection started the problem [6,10].

How swelling and poor drainage lead to sinusitis

A healthy sinus lining makes thin mucus [8,9]. Cilia move this mucus toward narrow openings in the nose [8].

Mucus helps trap germs and other particles [8]. Normal drainage then carries those materials out of the sinuses [8].

Inflammation can swell the lining and close the drainage points [8,10]. Mucus may then thicken or stay trapped [8,9].

This process can cause congestion, facial pain, and pressure [8,9]. It also explains why sinusitis often follows a cold [5,10].

Allergies can cause a similar drainage problem [6,10]. They may swell the nose and sinus tissues without a viral illness [6,10].

Factors that raise the risk of sinus problems

The following factors can raise the risk of sinus infections:

• A recent cold [1]
• Seasonal allergies [1]
• Smoking [1]
• Exposure to secondhand smoke [1]
• Physical problems inside the nose or sinuses [1]
• Nasal growths, including polyps [1,6]
• A weak immune system [1]

Nasal polyps are growths on the lining inside the nose [1]. They can block airflow or sinus drainage [1,6].

Other physical problems can also narrow the sinus openings [1,6]. This can make fluid buildup more likely [1].

A risk factor does not prove that bacteria caused current symptoms. Diagnosis depends on the full symptom pattern and an exam [1,4].

Diagnosis and Sinus Infection Treatment

Sinus infection treatment depends on the likely cause [1,4]. Symptom strength and illness length also guide care [1,4].

Many simple acute cases improve with time and supportive care [5,7]. Antibiotics are not needed for many sinus infections [1].

How a healthcare professional diagnoses sinusitis

A clinician usually starts by asking about symptoms [4]. The clinician will also ask how long the symptoms have lasted [4].

The exam may include checking the face for sore areas [4]. A clinician may also look inside the nose [4].

Imaging is not usually needed for simple acute sinusitis [4]. A CT scan can show details of the sinuses and nasal area [4].

A clinician may use imaging to rule out another cause [4]. It may also help when symptoms are not simple or short-lived [4].

Lab tests are not common for routine acute sinusitis [4]. A clinician may collect a sample if treatment does not help [4]. Samples may also help when symptoms get worse [4].

A nasal endoscopy may sometimes be used [4]. This test uses a thin, lighted tube to look inside the nose [4].

Home care and over-the-counter symptom relief

Many people with acute viral sinusitis get better with home care [5,7]. Home treatment aims to ease symptoms while the illness improves.

Rest may make recovery easier to manage. Drinking fluids can also support comfort during an upper airway illness.

A saline rinse can help clear mucus from the nose. Follow all product directions when using any nasal rinse.

Warmth placed over the face may feel soothing. It does not show whether the cause is viral or bacterial.

Some over-the-counter decongestants may ease acute sinus symptoms [7]. These medicines are not right for everyone.

Read the product label before taking an over-the-counter medicine. Ask a pharmacist or clinician if you have health concerns.

People who take other medicines should also ask about possible interactions. Pregnant adults should seek advice before choosing a new medicine.

Do not give medicine made for adults to children. Ask a healthcare professional which products are suitable for a child.

When antibiotics may be appropriate

Many sinus infections do not need antibiotics [1]. Antibiotics work against bacteria, not viruses [1,3].

Viruses cause most acute sinusitis cases [3]. This is why antibiotics often provide no benefit for a short viral illness [1,3].

A healthcare professional should decide whether bacteria are likely [1]. The decision is based on symptoms, their strength, and their length [1,4].

Symptoms lasting more than 10 days without improvement are an important clue [1,7]. Severe symptoms may also raise concern for bacteria [1].

Worsening after early improvement is another key pattern [1,5,7]. A clinician may use these signs to decide whether antibiotics are suitable [1].

Confusing a cold with sinusitis can lead to antibiotic overuse [3]. Careful assessment can help limit unneeded treatment [1,3].

Follow the prescriber’s directions if you receive an antibiotic. Contact the prescriber if your symptoms keep getting worse.

When specialist care may be needed

More testing may be useful when symptoms keep returning [2,4]. It may also be needed when symptoms last over 12 weeks [2,5].

A clinician may order more tests if treatment does not help [4]. Endoscopy, imaging, or sinus samples may help find the cause [4].

Long-term blockage may relate to allergies or nasal polyps [1,6]. Other physical problems can also stop normal sinus drainage [1,6].

A specialist can look for causes of repeat or long-term symptoms. The findings may guide further sinus infection treatment [4].

When to See a Doctor

The timing and pattern of symptoms can guide the choice to seek care [1,4]. Mucus color alone should not guide that choice [1,3].

Reasons to schedule a medical appointment

Contact a healthcare professional if:

• Symptoms last more than 10 days without improving [1,7].
• Symptoms improve but then become worse [1,5].
• Symptoms are severe [1].
• Sinus infections keep coming back [2,10].
• Symptoms last longer than 12 weeks [2,5].
• Symptoms worsen or do not improve with treatment [4].

These patterns may need an exam for bacterial or chronic sinusitis [1,2]. Allergies or a physical blockage may also need to be checked [1,6].

A clinician can decide whether tests or antibiotics are right [1,4]. The clinician may also suggest care from a specialist [4].

People with weak immune systems have a higher risk of sinus problems [1]. They should ask a clinician for advice based on their health needs.

Tell the clinician about any recent infections. Also share your medicines, health problems, and past sinus symptoms.

Emergency sinus infection warning signs

Rare sinus problems can become serious. Eye swelling or vision changes may signal a complication near the sinuses [5,8].

A severe headache, stiff neck, or confusion may also signal a rare complication. These symptoms require urgent medical assessment.

Seek urgent care for:

• Swelling or redness around an eye
• New vision changes
• A severe or unusual headache
• A stiff neck
• Confusion or a major change in awareness

Do not wait for a normal visit when these warning signs occur. The eyes and other key parts of the face sit close to the sinuses [5,8].

Preventing recurrence and protecting sinus health

Smoking and secondhand smoke are risk factors for sinus infections [1]. Reducing smoke exposure may help protect sinus health [1].

Seasonal allergies are another known risk factor [1]. Managing allergies may reduce swelling that blocks drainage [1,6].

Acute sinusitis often follows a cold [1,5]. Washing your hands can help limit the spread of common infections.

Use nasal-rinse products as directed. Keep the rinse device clean and follow the product instructions.

Seek medical advice for symptoms that keep returning. Repeat problems may relate to allergies, nasal polyps, or narrow sinus openings [1,6].

Conclusion

Most acute sinus infections are caused by viruses [3,5]. They often improve within seven to 10 days without antibiotics [5,7].

Home care may ease discomfort while the swelling improves [5,7]. Many people do not need antibiotic sinus infection treatment [1].

Knowing sinus infection symptoms, causes, treatment and when to see a doctor can guide safe choices. Seek care if symptoms last more than 10 days without improvement [1,7].

Also seek care for severe symptoms or decline after early improvement [1,5]. Repeated or long-term symptoms should also be checked [2,4].

Eye swelling, vision changes, severe headache, stiff neck, or confusion need urgent assessment. A healthcare professional should decide whether antibiotics or further tests are needed [1,4].