When a Sinus Infection Needs Antibiotics
Sinus infections, or sinusitis, occur when the hollow cavities around the nose become inflamed and swollen. Most begin as viral infections following a cold or allergy flare, leading to congestion, pressure, and nasal discharge. Because viruses cause the majority of cases, antibiotics are not usually needed at first. The body’s immune system can often resolve mild sinus infections on its own within a week.
Doctors consider antibiotics only when signs point to a bacterial sinus infection. Key clues include symptoms that last longer than ten days without improvement, severe facial pain or swelling, thick yellow or green discharge accompanied by fever, or symptoms that improve briefly but then worsen again. These patterns suggest bacteria such as Streptococcus pneumoniae, Haemophilus influenzae, or Moraxella catarrhalis have taken hold after a viral illness. Using antibiotics too soon or unnecessarily can do more harm than good. Overuse contributes to antibiotic resistance and exposes patients to side effects like stomach upset, diarrhea, or allergic reactions. Medical guidelines recommend a “watchful waiting” approach for the first few days if symptoms are mild. Supportive care, such as rest, hydration, saline rinses, and pain relief, often brings gradual recovery without antibiotics.
When symptoms persist beyond ten days, become severe, or interfere with daily activities, a healthcare professional can evaluate whether antibiotics are appropriate. The decision depends on age, medical history, and whether similar infections have occurred before. Bacterial sinusitis usually responds well once the correct antibiotic is started and the full treatment course is completed.
First-Line Antibiotics and How They Work
When bacterial sinusitis is diagnosed, the first-line antibiotic in most guidelines is amoxicillin or amoxicillin–clavulanate (also known by the brand name Augmentin). Amoxicillin belongs to the penicillin family and works by interfering with bacterial cell-wall synthesis, causing the bacteria to break apart and die. The addition of clavulanate helps overcome bacterial resistance by blocking enzymes called beta-lactamases that would otherwise destroy the antibiotic.
For adults, the typical course lasts five to ten days, while children often require a slightly longer regimen. The shorter five-day schedule has been shown to be just as effective for most uncomplicated infections, reducing both side effects and the risk of resistance. Patients who start feeling better before finishing their prescription must still complete the entire course to ensure the infection clears completely. For people allergic to penicillin, several alternatives exist. Doxycycline, a tetracycline-class antibiotic, is a common substitute. It prevents bacteria from making proteins necessary for growth. Macrolides such as azithromycin or clarithromycin are sometimes used, though resistance has become more frequent among Streptococcus pneumoniae. In more severe cases or when resistance patterns are known, doctors may turn to cephalosporins such as cefuroxime or cefixime.
Local resistance rates vary, so a treatment that works well in one region may be less effective in another. Physicians rely on regional data and sometimes culture results from nasal or sinus samples to guide the best choice. Regardless of the drug used, antibiotics work most effectively when started at the right time and paired with good supportive care, such as adequate hydration, nasal saline irrigation, and rest.
When to Use Second-Line or Broad-Spectrum Options
Sometimes a sinus infection does not improve despite appropriate first-line antibiotics. If symptoms persist beyond three to five days of treatment or worsen after initial relief, doctors may switch to a broader or second-line antibiotic. This can happen when the bacteria are resistant to the initial drug, the infection is unusually severe, or underlying factors such as allergies, nasal polyps, or a weakened immune system make recovery slower.
Second-line options include levofloxacin and moxifloxacin, two fluoroquinolone antibiotics that penetrate sinus tissues effectively and act on a wide range of bacteria. They are generally reserved for patients who cannot tolerate first-line agents or whose infections are complicated. Because fluoroquinolones can cause side effects such as tendon inflammation, nerve pain, or effects on blood sugar, they are used cautiously and only when clearly necessary. Another alternative for resistant infections is a combination of cefixime and clindamycin. Cefixime targets Gram-negative bacteria, while clindamycin works against Gram-positive and anaerobic organisms, offering broader coverage. In chronic or recurrent sinusitis, treatment may also include imaging studies or referral to an ear, nose, and throat specialist to look for structural problems that contribute to infection.
It is important to avoid using broad-spectrum antibiotics unless directed by a healthcare professional. Unnecessary escalation increases the risk of resistance and disrupts healthy bacteria in the body. Once improvement begins, symptoms typically fade within a few days, though congestion and fatigue may linger as the sinuses heal. Completing the full antibiotic course remains essential to prevent relapse or chronic inflammation.
Supportive Care and Prevention
Antibiotics are only one part of treating a sinus infection. Supportive care helps relieve discomfort and promotes healing even when antibiotics are prescribed. Saline nasal sprays or rinses clear mucus and bacteria from the nasal passages, reducing pressure and congestion. Breathing warm, moist air from a humidifier or taking a steamy shower can loosen thick secretions and ease sinus drainage. Over-the-counter pain relievers such as acetaminophen or ibuprofen help reduce fever and relieve facial pain.
Decongestant sprays can temporarily shrink swollen nasal tissues, but they should not be used for more than a few days, as longer use may cause rebound congestion. Rest, adequate hydration, and avoiding cigarette smoke or strong odors all support recovery. In allergic individuals, antihistamines and nasal corticosteroids can prevent future sinus inflammation and reduce the likelihood of recurrent infections. Preventive steps play an equally important role. Washing hands regularly, managing seasonal allergies, and getting vaccinated against influenza and pneumococcal bacteria can reduce the risk of developing bacterial sinusitis. People who experience frequent sinus infections should discuss potential underlying issues, such as deviated septum, nasal polyps, or chronic allergies with an ear, nose, and throat specialist.
Above all, antibiotics should never be shared or saved for later use. Taking leftover medication can mask symptoms without fully clearing the infection. If pain or swelling around the eyes, vision changes, or persistent high fever develop, it is essential to seek medical help immediately, as these signs can indicate that the infection has spread beyond the sinuses.
References
- Infectious Diseases Society of America. (2012). Clinical practice guideline for acute bacterial rhinosinusitis in children and adults. Clinical Infectious Diseases, 54(8), e72–e112. https://academic.oup.com/cid/article/54/8/e72/455098
- National Health Service. (2025, February 5). Sinusitis (sinus infection). https://www.nhs.uk/conditions/sinusitis/