Bactrim for Sinus Infection: Is It a Good Option?

Sinus infections are incredibly unpleasant illnesses that cause your face, specifically your cheeks and temples, to be in pain while also leaving you congested. When we’re sick, we often want to get an antibiotic prescription to start feeling better, but antibiotics aren’t always effective. 

Bactrim is an antibiotic often prescribed for various bacterial infections, but sinus infections are not one of them. This is because the bacteria that cause sinus infections are often resistant to Bactrim, so the antibiotic is ineffective. Continue reading to learn more about why Bactrim is not a good option for sinus infections and what antibiotics are better choices. 

Table of Contents

What Are Sinus Infections?

A sinus infection, which might also be referred to as rhinosinusitis or sinusitis, causes inflammation in the sinuses and the inside of the nose. Most sinus infections result from viruses, but around 2% of cases result from bacterial infections. 

Those with a sinus infection may have symptoms such as:

  • facial pain
  • nasal congestion
  • headache
  • sore throat
  • green or yellowish nasal drainage

About Bactrim

Bactrim is an antibiotic containing a combination of trimethoprim and sulfamethoxazole. These are two antibiotics that each target a stage in bacteria’s protein production process, making it so that bacteria cannot survive. Since they target different parts of the production process, they also treat different types of bacterial infections, and combining the two drugs into one medication allows Bactrim to treat a broader range of infections than trimethoprim or sulfamethoxazole could individually. 

Of note, as an antibiotic, Bactrim is only effective against bacterial infections, not viral ones. This means that it doesn’t always treat an infection. For example, Bactrim can be prescribed to treat UTIs from bacterial causes, but not from viral. The same is true for sinus infections. 

Does Bactrim Treat Sinus Infections?

While Bactrim can treat sinus infections resulting from bacteria, it is not generally a first-line approach. Instead, the first choice for treating sinus infections is generally amoxicillin or amoxicillin/clavulanate. 

If someone has a penicillin or cephalosporin allergy, Bactrim may then be used as a treatment for sinus infections. Additionally, Bactrim may be considered in cases where the first treatment option did not work.

However, there has been a growing number of cases showing bacterial resistance to Bactrim, which means that Bactrim does not make the infection go away. This makes Bactrim a less effective treatment for those with a sinus infection, and as a result, it is often not recommended to treat a sinus infection.

How Effective Is Bactrim for Treating Sinus Infections?

Since most sinus infections result from a viral infection, Bactrim is not usually effective. Even more, in the cases where the infection is bacterial, a growing number of cases show antibiotic resistance to Bactrim by the bacteria most often responsible for bacterial sinus infections, Streptococcus pneumoniae

Because of this, Bactrim is generally ineffective against sinus infections and is often only considered in cases where other antibiotics have been unsuccessful. 

Side Effects of Bactrim

The most common side effects for those on Bactrim include those affecting the gastrointestinal system, such as stomach pain, nausea, vomiting, and diarrhea. When these side effects appear, it is often recommended to take Bactrim with food to help mitigate these symptoms. 

Bactrim can also increase your sensitivity to the sun, making you more likely to get sunburned. Because of this, avoiding sunlight while on Bactrim is recommended, and if you do have to spend time outside, wear protective clothing and sunscreen. 

Some people may experience an allergic reaction to Bactrim, which can include symptoms such as coughing, hives, shortness of breath, and swelling in the throat, mouth, or face. Yet another reaction to Bactrim includes severe skin reactions, which can cause skin pain, peeling skin, and a purple or red rash with blistering. Sometimes, it may also manifest with burning eyes. If you experience any of these symptoms while on Bactrim, seek immediate medical attention. 

Finally, Bactrim can cause liver problems in some individuals. If you notice darkening urine, lightening stool, stomach pain, or yellowing of your eyes or skin (jaundice), seek medical attention. 


Will Bactrim Clear up a Sinus Infection?

Bactrim might clear up the sinus infection if the sinus infection is due to a bacterial infection. However, the bacteria most often responsible for bacterial sinus infections is Streptococcus pneumoniae, which is showing more and more resistance to Bactrim. So, if this bacteria is responsible for the sinus infection, Bactrim may not be able to clear up the infection. 

Is Bactrim Good for Sinus Infection?

Bactrim is not often recommended as a first-line treatment for sinus infections. Most sinus infections are viral, meaning no antibiotic will be effective against them. Then, in the cases where the sinus infection is from bacteria, they are often resistant to Bactrim. 

How Much Bactrim Should I Take for a Sinus Infection?

If you have been prescribed Bactrim for a sinus infection, follow the dosage instructions provided by your doctor or pharmacy. The typical dose for Bactrim is 800 mg/160 mg of sulfamethoxazole/trimethoprim every 12 hours. 

What Is the Best Antibiotic for a Sinus Infection?

Those with a sinus infection from a bacterial cause are often prescribed amoxicillin or amoxicillin/potassium clavulanate (Augmentin). Doxycycline, levofloxacin, and moxifloxacin are alternatives for those with a penicillin allergy. 

When to See a Doctor?

If you are feeling under the weather and suffer from facial pain, headache, nasal congestion, sore throat, and green or yellow nasal drainage, it’s recommended to see a doctor as you likely have a sinus infection. 

Antibiotics are not always prescribed, but you may be more likely to be prescribed them if your symptoms are severe, they are getting worse, or they have lasted 10 days and have not gotten better.

With DrHouse, you can meet with an online doctor in just 15 minutes to discuss your symptoms and receive an antibiotic prescription, if needed. 

Key Takeaways

Sinus infections cause inflammation of the sinuses and nose, which can result in unpleasant symptoms such as facial pain, congestion, and headaches. However, most sinus infections result from viruses, so the only thing you can do is manage the symptoms and wait for the infection to go away on its own. 

In 2% of cases, the infection is from bacteria, in which case an antibiotic can be prescribed to treat the infection. However, some antibiotics, such as Bactrim, are ineffective against the bacteria that cause sinusitis. This is why they are not often prescribed, although they can be in some instances. 

If you have facial pain and congestion that is worsening or lasting for 10 days, reach out to a doctor about an antibiotic prescription, of which amoxicillin is often the most common. 


Content on the DrHouse website is written by our medical content team and reviewed by qualified MDs, PhDs, NPs, and PharmDs. We follow strict content creation guidelines to ensure accurate medical information. However, this content is for informational purposes only and not a substitute for professional medical advice, diagnosis, or treatment. For more information click here.

Always consult with your physician or other qualified health providers about medical concerns. Never disregard professional medical advice or delay seeking it based on what you read on this website.

If you are experiencing high fever (>103F/39.4C), shortness of breath, difficulty breathing, chest pain, heart palpitations, abnormal bruising, abnormal bleeding, extreme fatigue, dizziness, new weakness or paralysis, difficulty with speech, confusion, extreme pain in any body part, or inability to remain hydrated or keep down fluids or feel you may have any other life-threatening condition, please go to the emergency department or call 911 immediately.

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