Flu, Dengue or COVID? How to Tell the Difference and When to See a Doctor

Flu-like illness is on the rise again. According to the Department of Health, influenza-like illness (ILI) cases went up by 31% in the first two weeks of October 2026 compared with the two weeks before, with the biggest increases in Western Visayas, MIMAROPA, and Central Visayas. At the same time, dengue cases are still rising in some areas. Since many of these illnesses start with fever and body aches, it can be hard to tell them apart at home. This guide helps you understand the differences and know when to see a doctor.

Important: symptoms overlap a lot. Only a doctor, often with the help of laboratory tests, can tell which illness you have. Use this guide as orientation, not as a diagnosis.

Symptoms at a Glance

	Flu (trangkaso)	Dengue	COVID-19	Leptospirosis
Start	Sudden	Sudden high fever	Gradual or sudden	Sudden, usually 2–30 days after contact with floodwater or mud
Fever	Common	High, often 2–7 days	Common	High
Cough, sore throat, runny nose	Common	Uncommon	Common	Uncommon
Body and muscle pain	Common	Severe; pain behind the eyes, joints, and bones	Common	Severe, especially in the calves
Rash	Rare	Common, often a few days into the illness	Occasional	Occasional
Loss of taste or smell	Rare	Rare	Possible	Rare
Red eyes	Occasional	Occasional	Occasional	Common
Bleeding (gums, nose, skin spots)	No	Possible, a warning sign	No	Possible in severe cases

Flu (Influenza)

The flu usually starts suddenly with fever, chills, headache, body aches, cough, and sore throat. Most healthy people recover in about a week with rest and fluids. Flu can become serious in young children, older adults, pregnant women, and people with chronic illnesses, mainly through complications such as pneumonia. A yearly flu vaccine lowers the risk of severe illness.

Dengue

Dengue typically causes a sudden high fever, severe headache, pain behind the eyes, joint and muscle pain, and sometimes a rash. Cough and runny nose are uncommon. The most dangerous period is often when the fever goes down, around day 3 to 7, because that is when severe dengue can develop. A doctor can request a blood test such as a CBC (platelet count) and a dengue test. Read more in our dengue guide.

If you suspect dengue, avoid pain relievers such as ibuprofen or aspirin unless a doctor tells you otherwise, because they can increase the risk of bleeding.

COVID-19

COVID-19 can look very much like the flu: fever, cough, sore throat, tiredness, and body aches. Loss of taste or smell is possible but less common than in earlier waves. A rapid antigen test can help, but a negative result does not rule out COVID-19 completely, especially early on. People at high risk of severe illness should talk to a doctor early.

Leptospirosis

If you waded through floodwater or mud in the past few weeks and now have a fever, severe muscle pain (especially in the calves), headache, or red eyes, tell your doctor about the exposure. Leptospirosis needs prompt treatment with antibiotics prescribed by a doctor. See our leptospirosis guide.

Warning Signs: Go to the Emergency Room

• Difficulty breathing or chest pain
• Severe abdominal pain or persistent vomiting
• Bleeding from the gums or nose, blood in vomit or stool, or black stools
• Confusion, extreme sleepiness, or seizures
• Cold, clammy hands and feet, or fainting
• Little or no urine for more than 6–8 hours
• Yellowing of the skin or eyes
• In babies and children: refusing to drink, unusual drowsiness, or fast breathing

In an emergency, call 911 or go to the nearest hospital.

When to See a Doctor

• Fever that lasts more than 2 days, or very high fever
• Any fever in a baby under 3 months
• Fever after contact with floodwater
• If you are older, pregnant, or have a chronic illness such as diabetes, heart, kidney, or lung disease
• If you feel better and then suddenly get worse

Protect Others While You Are Sick

The DOH reminds the public to cover the mouth and nose when coughing or sneezing, to stay at home when experiencing flu-like symptoms, and to keep indoor spaces well ventilated. Wash your hands often, and consider wearing a mask around older or sick family members. To prevent dengue, remove standing water around your home and use mosquito repellent.

Find an internist, a pediatrician, or an infectious disease specialist near you on MyDoktor.ph, or use our symptom checker to see which kind of doctor fits your symptoms.

This article is for general information and does not replace advice from your doctor. Symptoms overlap, and only a doctor can make a diagnosis.