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FACT SHEET: Influenza (also known as “flu” and “seasonal influenza”; caused by various subtypes of influenza viruses A, B, and C)1

Date of Publication: December 11, 2013

Is the initiation of non-invasive dental hygiene procedures* contra-indicated?

  • Yes, if the patient/client has active disease and/or is contagious.

Is medical consult advised? 

  • If a person exhibits signs and symptoms of influenza (see below), refer to primary care provider (e.g., physician or nurse practitioner) for definitive diagnosis (clinical +/- laboratory) and management. Persons at greater risk for developing serious complications include older people, young children, pregnant women, people with certain chronic health conditions (e.g., diabetes, heart disease, cancer, and asthma), and persons living in nursing homes. The patient/client should be instructed to reschedule dental hygiene appointment when s/he feels well and is non-infectious.

Is the initiation of invasive dental hygiene procedures contra-indicated?**

  • Yes, if the patient/client has active disease and/or is contagious. 

Is medical consult advised? 

  • See above.

Is medical clearance required? 

  • No.

Is antibiotic prophylaxis required?  

  • No.

Is postponing treatment advised?

  • Yes, during the period of communicability (see below).

Oral management implications

  • Mode of transmission is via contact with respiratory secretions (e.g., sputum and nasal mucus) of infected people. Infection occurs mainly by droplet spread (e.g., coughing, sneezing, and talking); these droplets can land in the mouths or noses of nearby persons. Less commonly, persons may acquire influenza by touching surfaces or objects that have flu virus on them, and in turn touching their own mouth, eyes, or nose.  
  • Influenza is highly contagious. Most healthy adults are capable of infecting others beginning from one day before overt symptoms develop and up to 5 to 7 days after becoming ill. In young children, virus shedding can last 7 to 10 days, and immunocompromised persons may be capable of infecting others for an even longer time.
  • Annual influenza immunization (typically during the Canadian autumn to protect against peak activity in the winter) is recommended for all persons (without contraindications) aged 6 months and older, and it is publicly funded in Ontario.  Because the predominant circulating subtypes of influenza virus continually change, the seasonal flu vaccine is re-formulated every year to protect against the three or four influenza viruses that research suggests will be most common. The injectable form of the vaccine is inactivated and cannot cause influenza. A live, attenuated nasal-spray vaccine also exists, but it is less commonly used and is not always publicly funded in Ontario.
  • In the absence of contraindications, all healthcare workers, including dental hygienists, should be annually vaccinated to protect themselves and reduce spread to others.

Oral manifestations

  • Sore throat, enlarged tonsils, and erythema of oropharyngeal mucosa and tonsils.

Related signs and symptoms

  • Seasonal influenza results in annual epidemics of varying severity, and sporadic cases or outbreaks may occur outside of typical seasonal patterns. 
  • Influenza typically presents with a headache, chills, and cough (usually dry), followed by fever, decreased appetite, muscle aches, fatigue, runny nose, sneezing, watery eyes, and sore throat. Nausea, vomiting, and diarrhea may also occur, particularly in children. 
  • Most affected persons recover from seasonal influenza in 7 to 10 days. Treatment is primarily symptomatic, although oral antiviral medication may be indicated in certain circumstances. 
  • Children younger than 2 years, persons older than 64 years, and persons with chronic diseases (such as diabetes and heart disease), are at elevated risk of serious complications (e.g., pneumonia). About 3,500 Canadians die of influenza and its complications annually.

References and sources of more detailed information

Date: September 23, 2013
Revised: February 20, 2020


1 In additional to seasonal influenza (the focus of this fact sheet), humans can also be infected with influenza viruses that circulate in animals, such as birds (“avian flu”) and pigs (“swine flu”). Usually human infections of zoonotic influenza are acquired through direct contact with animals or contaminated environments, and they do not tend to spread very far among humans. However, epidemic or pandemic potential in humans can result from zoonotic virus adaptation or acquisition of certain genes from human viruses.

* Includes oral hygiene instruction, fitting a mouth guard, taking an impression, etc.
** Ontario Regulation 501/07 made under the Dental Hygiene Act, 1991. Invasive dental hygiene procedures are scaling teeth and root planing, including curetting surrounding tissue.