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Antivirals work within 48 h

It's not "just a cold"It's influenza, and it does matter.

If you've had a high fever and body aches for only a few hours, there is a treatment that shortens the illness, but it only works if started in time.

You have less than 48 h from the first symptom for the treatment to have its greatest effect. Every hour counts.
48h
Antiviral window
5–7d
Days in bed
Oct–Mar
Season in Mexico City
48h
That's the antiviral window.
After that, its effect drops sharply.
Sudden fever 38–40 °C (100.4–104 °F)
Dry cough + body aches
Count the hours, not the days

How it feels

It hits all at once, not little by little

Unlike a cold, influenza sweeps through you in a few hours. If you recognize two or more of these signs, don't wait.

Sudden fever

38–40 °C (100.4–104 °F) in a few hours

Body aches

"Even my hair hurts"

Dry cough

Intense and exhausting

Extreme fatigue

You can't even get up

Why timing matters

What changes when you take the antiviral in time

Treatment reduces duration, complications and household spread, as long as it is started within 48 h.

Real difference

Antiviral within the first 48 h vs no treatment

With antiviral
−1.5 days

less fever and symptoms

  • Faster recovery
  • Lower risk of pneumonia
  • Less spread at home
  • Lower chance of hospitalization
vs
Without treatment
5–7 days

of fever, aches and exhaustion

  • A cough that lasts weeks
  • Higher risk of bacterial pneumonia
  • More spread to your family
  • Worse course if you have a chronic disease
Who gets complications?

Influenza is not equally dangerous for everyone

If you belong to any of these groups, influenza can turn into pneumonia quickly. An early evaluation changes the outcome.

65 and older

An immune system that is slower to stop the virus.

Asthma or COPD

The virus triggers flare-ups and lowers oxygen levels.

Diabetes or heart disease

Systemic inflammation destabilizes the underlying condition.

Pregnancy or children

Higher risk of lung complications and hospitalization.

Urgent warning signs

This cannot wait until tomorrow

If your influenza shows any of these signs, seek medical attention that same day:

Go to the emergency room or call us if:

  • You're short of breath or breathing fast
  • Chest pain or pressure
  • Bluish lips or nails
  • Fever lasting more than 4 days
  • Oxygen saturation below 92%
  • Confusion or trouble waking up fully
Fast track to your visit

From your message to treatment, in under 24 h

When it's influenza, every hour matters. That's why the path to your appointment is designed to be short and direct.

Min 0

You send a WhatsApp

I answer you personally, no filters or bots.

Same day

Priority slot

An appointment reserved for acute fever cases.

20 min

Full evaluation

Clear diagnosis and oxygen level measured —in person or by teleconsultation.

Within 48 h

Treatment prescribed

A personalized plan, with you from start to finish.

Priority appointment · Antiviral within the window

Don't wait to "see if it passes".
The first 48 hours are the ones that count.

Same-day evaluation and a clear plan so influenza doesn't end in the hospital.

Book my appointment

Frequently asked questions about influenza

What patients ask me most often when the season arrives.

How can I tell influenza apart from a common cold?

Influenza starts abruptly with high fever (38–40 °C / 100.4–104 °F), intense muscle aches, marked fatigue, headache and a dry cough. A cold comes on more gradually, without high fever; nasal congestion predominates and symptoms are milder. Influenza lasts 5–7 days; a cold, 3–5.

When is influenza dangerous?

When there is difficulty breathing, chest pain, oxygen saturation below 92%, fever persisting more than 4 days or general deterioration, and whenever it affects pregnant women, adults over 65, young children or people with asthma, COPD, diabetes or immunosuppression.

Does the flu vaccine work?

Yes. It reduces the risk of severe disease, hospitalization and death, especially in older adults and patients with chronic illness. Protection is not total because the virus changes every season, but vaccinated people who do get sick have a milder course.

How much does a flu consultation cost in Mexico City?

Message us on WhatsApp at +52 55 9170 8334 to book a priority appointment if you have symptoms and get up-to-date prices.

Find me here

Hospital Santa Coleta

Saturnino Herrán 59
San José Insurgentes, Benito Juárez
03900 Ciudad de México, CDMX

Office hours

Monday to Friday: 4:00 PM to 9:00 PM

Saturday and Sunday: 12:00 PM to 4:00 PM

By Appointment

Important medical notice: The information on this site is educational and informational in nature, prepared by Dr. William César Lara Vázquez, and does not replace a consultation, diagnosis or treatment with a medical professional. If you have any respiratory symptom, see your doctor or the emergency service. In the event of a respiratory emergency, call 911.