Flu (Influenza): Symptoms, How Long It Lasts & Treatment
Quick answer: the flu (influenza) is a contagious respiratory illness that causes fever, body aches, cough, sore throat, and fatigue, usually appearing suddenly. Most people recover in one to two weeks with rest and fluids, but the flu can be dangerous for young children, adults over 65, and people with chronic conditions. Getting a yearly flu shot is the best way to protect yourself — available at Hospital CMQ along with 24/7 bilingual urgent care for visitors and residents.
What is the flu?
The flu, or influenza, is a contagious respiratory illness caused by influenza viruses that infect the nose, throat, and sometimes the lungs. It’s usually seasonal, with flu season in Mexico and much of the Northern Hemisphere running roughly from October to May, and typically peaking between December and February.
Most people can recover from the flu quickly and without major complications, achieving a full recovery in one or two weeks. Nevertheless, this disease should not be taken lightly, as it can be dangerous for kids and the elderly. Therefore, some flu complications can be deadly within these age groups if not treated properly. In the following article, we will share with you ten important facts about the flu.
Visiting Puerto Vallarta and feeling flu symptoms?
Our bilingual medical team offers testing, treatment, and flu shots — 24/7 urgent care available.
What are the symptoms of the flu?
Flu symptoms usually come on suddenly and can include:
- Fever or feeling feverish (not everyone with the flu runs a fever)
- Cough, often dry and persistent
- Sore throat
- Runny or stuffy nose
- Body aches and headache
- Chills and sweats
- Fatigue
Unlike a cold, which usually comes on gradually, the flu tends to hit hard and fast — it’s common to feel fine one day and quite unwell the next
Flu vs. cold vs. COVID-19: what’s the difference?
| Symptom | Flu | Common cold | COVID-19 |
| Onset | Sudden | Gradual | 2-14 days after exposure |
| Fever | Common, can be high | Rare | Common |
| Body aches | Common, often severe | Mild | Common |
| Loss of taste/smell | Rare | Rare | Common |
| Severity | Can be severe | Usually mild | Can be severe |
Because these illnesses share so many symptoms, testing is the only reliable way to know which one you have — especially important if you’re in a higher-risk group.
How long does the flu last?
Most people recover within one to two weeks. Fatigue and a lingering cough can sometimes last a bit longer. Antiviral medication, if started within 48 hours of symptom onset, can shorten how long you’re sick and reduce the risk of complications.
How is the flu treated?
- Rest and plenty of fluids — water, broths, and electrolyte drinks; avoid sugary or caffeinated drinks
- Over-the-counter medication for fever and body aches
- Antiviral medication, prescribed by a doctor, most effective when started within 48 hours of symptoms starting
- A humidifier and warm fluids can help ease a stuffy nose and sore throat
When should I see a doctor?
Seek medical care right away if you experience:
- Difficulty breathing or shortness of breath
- Chest pain
- Persistent dizziness
- A fever above 104°F (40°C)
- Symptoms that improve and then come back or get worse
- Worsening of an existing chronic condition
You’re also at higher risk of flu complications if you’re pregnant, over 65, under 5 years old, or have a chronic condition such as asthma, diabetes, or heart disease — contact your doctor as soon as symptoms begin.
Can the flu be prevented?
- Get a yearly flu shot — it takes about two weeks to provide full protection, so getting it before flu season starts is ideal
- Wash your hands often with soap and water for at least 20 seconds
- Cover coughs and sneezes with a tissue or your elbow
- Avoid close contact with people who are sick, and stay home if you’re sick yourself
What about the flu shot? Is the flu shot effective? Does the flu shot have side effects?
The Influenza vaccine is highly effective, although it can take up to two weeks to start providing the needed protection against this illness. Therefore, getting the this vaccine is one of the best ways to protect ourselves from the influenza virus. In order to get the best protection, it is extremely important to get this vaccine before the flu season starts.
But why is it effective? This shot is effective because it helps our body to develop special antibodies that protect it from this virus. However, we should note that this vaccine does not have an immediate protective effect, as it can take up to two weeks for it to be effective. In addition, we should not expose ourselves to a person infected with the virus during the two weeks after getting this shot, as we can acquire the illness during this time. According to the Centers for Disease Control and Prevention, the best time to get the Influenza vaccine is in October. Although it is considered safe, and less than 5% of the people who get it will experience mild side effects, it’s important to consider them. The flu shot’s side effects are normally mild and will disappear on their own after one or two days. Some common mild side effects include:
- Headaches
- Fever
- Muscle aches
- Swelling and soreness from the shot
- Mild nausea
Is it necessary to get the Influenza vaccine every year?
Yes, you do need to get this vaccine every year.
Remember that this season’s common virus, could not be the most common influenza virus next season. This is because, as with any virus, the influenza virus evolves and changes every year. Thus, it’s necessary to get your vaccine every year.
Frequently Asked Questions About The Flu
No. Seasonal influenza is a respiratory illness. “Stomach flu” is a common name for a different intestinal infection that causes diarrhea, cramping, nausea, and vomiting.
In many cases, yes — talk with your doctor, since some formulations don’t contain egg-based protein and others can still be given safely under medical supervision.
Usually one to four days, though it can take longer in some cases.
No. The injectable vaccine uses an inactivated (killed) virus and cannot cause infection.
Flu care and vaccination at Hospital CMQ
Whether you are a resident or visiting Puerto Vallarta, our bilingual team can test for the flu, prescribe treatment, and administer flu shots.