Back to All News & Events

A case study on acute rhinosinusitis (ARS): do no harm

Back to Messenger
May Messenger 2022, MD Snapshot-Prescribing, Prescribing | Posted May 12, 2022
Read time: 7 minutes

Patient: Amy, a 55-year-old female.

Presenting complaint: Feeling unwell for about five days, “I don’t want this cold to go to my chest.”

History of present illness: Started with stuffiness and feeling unwell about five days ago, but now her nasal discharge is coloured and because her symptoms have lingered, she feels an antibiotic is needed. She can’t take time off work and needs to get better as soon as possible.

She describes green nasal discharge, facial pain (especially in the cheek area under the eyes), fullness of the ears and fatigue, but no fever. She has developed a slight cough over the last two days. She is on acetaminophen for the facial discomfort.

History: Occasional GERD, no previous sinusitis, no antibiotic use in the past month, no recent hospitalizations, no recent dental work, smokes occasionally (social events, when stressed), occasional use of alcohol.

Amy is allergic to minocycline, which causes a rash. She notes her mother is allergic to penicillin.

She is on no medications except OTC acetaminophen and acid blockers.

Exam: Afebrile, chest clear, no erythema over sinuses or real sinus tenderness, no tooth pain with pressure. Weighs more than 55 kg.

Social: Works full time for the Government of Alberta. She helps care for her four-year-old granddaughter and is the primary contact for her mother, who is in long-term care. Amy worries about spreading infection between family members.

Drug coverage: Amy has an employer-sponsored drug plan coverage.

Diagnosis: Acute rhinosinusitis (ARS).

A green cupboard full of medical supplies and boxes.              

What happens next?

Path A: The physician prescribes an antibiotic.


  • The diagnosis of ARS is clinical.
  • They feel antibiotics may prevent serious complications down the road.
  • The patient is demanding it, she is especially concerned because of her caregiver roles.
  • It helps the healthcare system as the patient won’t need to come back again or see another physician/specialist.
  • The patient has drug coverage to cover most of the costs.

Prescribing: The patient’s mother has had a severe reaction to penicillin in the past, so the patient is reluctant to take amoxicillin.

Rx: Levofloxacin 750 mg QD x 10 days (which was tolerated in the past).

Note: Current guidelines suggest a three-day course of levofloxacin in therapy of community-acquired pneumonia, and five days maximum in sinusitis.

Two weeks later:

Amy returns with the same head complaints and new gastrointestinal issues, worsening over six days:

  • Diarrhea several times daily, with cramping abdominal pain.
  • No appetite and nausea, no vomiting.
  • Has lost three kg since first becoming ill.
  • Inability to work, care for her granddaughter or visit her mother.

Exam: Abdomen tender but not peritonitic; active bowel sounds.

Diagnosis: probable C. difficile.

Order: C. diff toxin, CBC and diff, electrolytes and creatinine.

Rx: Vancomycin 125 mg po QID x 10d/Metronidazole 500 mg PO TID x 10 days.

One month later:

Amy returns reporting she was feeling better after the new drugs, but diarrhea has returned and she is too unwell to work. She’s lost another two kg.

Rx: Vancomycin 125mg PO QID x 10 days. Ask her not to take acid blockers if possible.

Three weeks later:

Again, an initial improvement in symptoms for about two weeks, then worsening. Feeling very unwell as before, plus she is now weak and dizzy. Further three kg weight loss. Daughter is now assisting her with household duties, etc.

Rx: Vancomycin 125mg PO QID + metronidazole 500mg PO TID x 14 days.

Two months later:

As she finished the vancomycin taper, Amy started to have looser stools with worsening the week after completion. Human Resources has advised she take short-term disability. Amy is worried she might pass C. diff to her family members. The overall low risk of this and home hygiene were discussed.

Down another two kg in weight.

Management: Restart Vancomycin taper protocol and refer for fecal microbiota transplant (FMT) as has third recurrence.

Amy remained on oral Vancomycin 125 po BID awaiting FMT and was ultimately successfully treated.


Path B: Do not prescribe an antibiotic.


The physician explains most rhinosinusitis is viral and even early bacterial infections get better with symptomatic management. They discuss Amy’s risk of antibiotic side effects and complications such as C. diff from unneeded antibiotics.

The physician reassures her the physical exam doesn’t show any red flags and improvement over the next five days is expected. They lay out a symptom management plan and agree she should call if she isn’t improving over that time.


While physicians often perceive that patients want antimicrobial therapy following a visit for an upper RTI, evidence suggests that many really want reassurance.

What can you do to reduce unnecessary prescribing and improve patient satisfaction?

  1. Simple measures can prepare patients for the antibiotic discussion and reinforce physicians’ commitment to appropriate prescribing. Studies show simply displaying a poster in your waiting rooms confirming the health care team is committed to using antibiotics properly educates patients, contributes to shared decision-making and helps decrease unneeded antibiotic prescriptions. A poster called Your Health is Important to Me is available online, and resources can be found at Choosing Wisely Canada.
  2. Have a discussion script in mind for when patients come with upper respiratory tract infection (URTI) symptoms, including:
  • Acknowledging the patient is unwell and validate the appropriateness of their visit.
  • Explaining the unlikelihood of a bacterial infection and the possible reasons for the symptoms:
    • 98% of ARS cases are viral in nature, so antibiotics will not help patients get better faster. Of the other 2%, 1.7% are bacterial but will resolve without antibiotics. Only 0.3% of ARS require antibiotics.
    • The symptoms of ARS are due to local swelling and accumulation of debris and mucous.
  • Setting reasonable expectations for the course of illness:
    • Acute viral infections tend to improve within one week, but complete improvement may take at least two weeks for resolution of all symptoms.
    • 85% of bacterial infections improve within two weeks, even without antibiotics.
    • Antibiotics for URTI do not shorten symptom duration or prevent complications in adults.
    • Coloured or purulent nasal discharge does not mean a bacterial cause.
  • Discuss the benefits and risks of antibiotic use:
    • Patients may not realize viruses are the main cause of URTIs and may not know that antibiotics do not help viral infections. Many patients also over-estimate the benefits of antibiotics and aren’t aware of antibiotic risks and possible side effects.
    • Adverse effects of antibiotics can include stomach upset, diarrhea, C. difficile colitis, subsequent infection with resistant bacteria or fungi, allergic reactions and heart rhythm issues with drug interactions (the majority of emergency department visits for antibiotic-related side effects are due to an allergic reaction).
  1. Share decision-making:
  • The prescriber felt Amy was expecting an antibiotic prescription, but after hearing about the low chance of benefit and possible harms, she was very willing to try symptomatic management with planned follow-up.
  • Evidence supports that decreased antibiotic prescribing in URTI is safe.
  • Refer the patient to for AMS and sinusitis resources.
  • If the patient is early in their course, a delayed prescription with a post-dated start date could be considered for patients who:
    • Have had symptoms for less than 10 days and whose symptoms have not worsened, and
    • Will only fill the prescription if symptoms do not improve after 10 days or worsen at any time.
  1. Offer detailed symptom management advice:
  • Nasal saline rinses, short-term decongestants, acetaminophen/ibuprofen, warm compresses.
  • Discuss prevention such as hand hygiene, humidifying the home and avoiding known/suspected allergens. In this case, encourage Amy to stop smoking and keep her immunizations up to date.
    • Preventative measures do help! According to the TPP Antibiotic Prescription Atlas 2020, there was a significant drop in antibiotic prescribing (almost 25% from 2019 to 2020) during the early part of the COVID-19 pandemic, suggesting a combination of decreased respiratory infections and less care-seeking for possible viral illnesses.
  • Give a viral prescription so the patient has something concrete to validate the illness and key information to refer to.
  • Educate about red flags patients should come in for:
    • A high fever (≥ 39°C) and purulent nasal discharge, or facial pain for three-to-four consecutive days at the beginning of illness, or
    • URTI symptoms that persist for at least 10 days or worsen after five-to-seven days with both nasal congestion/purulent nasal discharge, and facial pain/pressure (usually unilateral) +/-:
      • fever
      • maxillary toothache
      • facial swelling

A clipboard resting in a holder on the wall.

Supplementary information

Penicillin allergies:

  • A family history of penicillin allergy is not a reason to avoid penicillins altogether.
  • While 10% of patients report penicillin allergy, only 1% are truly allergic.
  • Resorting to the use of second-line therapies in lieu of penicillins can result in higher patient costs, increased risk of colonization with AROs, adverse effects, treatment failure and risk of  difficileinfection.
  • It is important to complete a detailed patient history to confirm a penicillin allergy.

When antibiotics are warranted for probable bacterial sinusitis:

Some guidelines recommend high-dose amoxicillin-clavulanate instead of amoxicillin for first line treatment of sinusitis due to high rates of penicillin-resistant S. pneumoniae and β-lactamase producing H. influenzae and M. catarrhalis, but high-dose amoxicillin remains a first-line option, given:

  • It has lower resistance rates in Canada.
  • Amoxicillin retains the best coverage of all oral β-lactam agents against S. pneumoniae (even majority of penicillin-resistant strains).
  • The higher incidence of adverse effects of amoxicillin-clavulanate
  • The need to limit broad spectrum antibiotic use to minimize the development of antibiotic resistance.

Macrolides, TMP/SMX, and oral cephalosporins are not recommended for empiric therapy of sinusitis due to unpredictable/poor activity against S. pneumoniae and/or H. influenzae.

Levofloxacin has good coverage of the pathogens involved. However, quinolones are not considered first-line empiric options for community bacterial infections due to increased risk of adverse events, excessively broad spectrum, potential for increasing resistance and increased risk of Clostridioides (Clostridium) difficile infection. Quinolones should be reserved for β-lactam allergic patients or patients who have failed first-line antibiotic therapy (reference: Bugs and Drugs).

ARS red flags

Red flags for complications of ARS are rare, with incidence being similar in those treated with antibiotics or placebo. Immediate attention is required if the patient has:

  • Double vision
  • Frontal swelling
  • Displaced globe
  • Ophthalmoplegia
  • Reduced visual acuity
  • Severe frontal headache
  • Periorbital edema or erythema
  • Neurological symptoms of meningitis

 C. difficile

  • Major risk factors for development of C. difficile infection include: treatment with antibiotics, proton pump inhibitors (PPIs), or antineoplastic agents within the previous eight weeks.
  • Rates of community-associated C. difficile infection appear to be increasing, another reason to use antibiotics judiciously.


  1. Antimicrobial Stewardship in Primary Care Continuing Education Program, School of Pharmacy, University of Waterloo
  3. RxFiles Antibiotics and Common Infections: Stewardship, Effectiveness, Safety and Clinical Pearls, October 2016
  4. NCBI Bookshelf, Acute Sinusitis, Continuing Education Activity,
  5. Incidence and economic burden of Clostridioides difficileinfection in Ontario: a retrospective population-based study;
  6. Emergency Department Visits for Antibiotic Associated Adverse Events;
  7. National Estimates of Emergency Department Visits for Antibiotic Adverse Events Among Adults – United States, 2011-1015;


Authors and reviewers:

Karen Smilski, BSc. Pharm, Pharmacist, CPSA Prescribing & Analytics

Dr. Mark Godel, MD, CPSA Medical Advisor

Fizza Gilani, BSc. Pharm, Program Manager, CPSA Prescribing & Analytics

Dr. Monica Wickland-Weller, MD, CPSA Senior Medical Advisor

Dr. Lynora Saxinger, MD, FRCPC, CTropMed, Co-Chair COVID-19 Scientific Advisory Group, Medical Lead AHS Antimicrobial Stewardship Northern Alberta, Physician Learning Program Stewardship Pillar Liaison

Comments for this post are now closed. If you would like to share your feedback on this topic, please email