Influenza (Flu)

Influenza is a highly contagious viral infection of the respiratory system. Influenza viruses are classified into types A, B, C, and D:

• Type A: Infects humans and some animals; commonly causes severe outbreaks.
• Type B: Can also cause epidemics but tends to result in less severe illness than type A.
• Type C: Rarely causes outbreaks and typically results in mild illness.
• Type D: Found in livestock and not known to infect humans.

Complications from influenza, such as pneumonia, are more likely in high-risk groups including:

• Elderly individuals (>65 years)
• Pregnant women
• Young children (<5 years)
• Patients with chronic illnesses (e.g., diabetes, asthma, heart disease)
• Immunocompromised individuals (e.g., HIV/AIDS, cancer patients)

Prevention

• Receive an annual influenza vaccination, especially if you are elderly, pregnant, have respiratory or heart conditions, or work in healthcare.
• Wash hands regularly with soap or alcohol-based hand sanitizers.
• Avoid touching the eyes, nose, or mouth to minimize the risk of infection after touching contaminated surfaces.

Self-Management

• Rest at home until fully recovered to prevent spreading the virus.
• Cover your mouth and nose when coughing or sneezing.
• Stay hydrated by drinking plenty of fluids.

When to See a Doctor

• Severe symptoms in:
  • Pregnant women
  • Children under 5 years
  • Elderly over 65 years
• Patients with:
  • Asthma
  • Chronic respiratory diseases
  • Diabetes
  • Heart disease
• Persistent high fever (>3 days) despite proper antipyretic use, combined with productive cough.
• Severe, continuous vomiting.
• Chest pain, difficulty breathing, rapid breathing, or wheezing.
• Confusion or inability to recognize people, time, or places.

Treatment Options

1. Analgesics and Antipyretics

• Paracetamol: 500–1,000 mg every 4–6 hours, with a maximum daily dose of 4,000 mg.

• Combination therapy: Paracetamol with NSAIDs (e.g., ibuprofen) may be used cautiously to manage fever and muscle aches, but NSAIDs should be avoided in suspected dengue fever due to bleeding risks.

2. Cough and Cold Preparations

Relieve symptoms such as fever, runny nose, or cough:

• Analgesics: Paracetamol, ibuprofen.
• Antihistamines: Brompheniramine, carbinoxamine, chlorphenamine, diphenhydramine, loratadine, triprolidine.
  
  • Some antihistamines can cause drowsiness; avoid driving or operating machinery after use.
• Decongestants: Pseudoephedrine.
  
  • Contraindicated in patients with cardiac arrhythmias, closed-angle glaucoma, urinary retention, and uncontrolled hypertension.
• Cough suppressants: Codeine, dextromethorphan.
  
  • Common side effects: drowsiness, constipation.

3. Antiviral Drugs

• Neuraminidase inhibitors (e.g., oseltamivir, zanamivir): Effective for treating uncomplicated influenza A and B if started within two days of symptom onset. Also used for prophylaxis.
• Adamantane M2 ion channel inhibitors (e.g., amantadine, rimantadine): Used for influenza A only.

• Antiviral drugs should be used under medical supervision. Patients must complete the prescribed course to prevent drug resistance.

4. Nasal Decongestants and Other Products

• Topical decongestants (e.g., naphazoline, oxymetazoline, tetrahydrozoline, xylometazoline): Provide rapid symptom relief.
  

  • Should not be used for more than five consecutive days to prevent rebound congestion.
  
  
  • Avoid in glaucoma, asthma, hypertension, heart disease, diabetes, or uncontrolled prostate enlargement.

• Saline nasal sprays or seawater solutions: Help moisturize the nasal mucosa, protect against viruses, and reduce congestion.

• Products containing carragelose: May trap and inhibit virus spread in the respiratory tract.

5. Nonsteroidal Anti-inflammatory Drugs (NSAIDs)

• NSAIDs (e.g., aspirin, ibuprofen, floctafenine, mefenamic acid, naproxen) can be used to reduce fever, pain, and inflammation.
  
  • Use cautiously in patients with peptic ulcers, asthma, heart or kidney disease, or dehydration.

• Salicylates (e.g., aspirin):
• Should be avoided in children under 19 years with viral infections to prevent Reye’s syndrome, a potentially fatal condition.

Vaccination

Annual influenza vaccination is the most effective way to prevent infection:

• Inactivated Influenza Vaccine (IIV):
  • Contains inactivated virus.
  • Recommended for individuals ≥6 months old.
  • Especially advised for pregnant women and people with chronic illnesses.
  • Administered intramuscularly.
  • Children aged 6 months to 8 years receiving influenza vaccine for the first time should receive two doses at least four weeks apart.
• Live Attenuated Influenza Vaccine (LAIV):
  • Contains live, weakened virus.
  • Administered intranasally.
  • Approved for healthy individuals aged 2–49 years who are not pregnant and have no chronic medical conditions.
  • Contraindicated in:
    • Children <2 years or adults ≥50 years
    • Children on salicylate therapy
    • Asthmatic children or those with a history of wheezing
    • Immunocompromised patients
    • Patients with cerebrospinal fluid leaks, cochlear implants
    • Recent use of antiviral medications (wait at least 17 days after last dose)
• Recombinant Influenza Vaccine (RIV):
  • Produced via cell-based techniques.
  • Approved for individuals ≥18 years old.