Fever and body aches: dengue, flu, COVID or chikungunya?

In Puerto Rico, a person with fever and body aches could have several different infections: dengue, influenza (flu), COVID-19, chikungunya and, less often, other respiratory viruses such as RSV. They all start with fever, tiredness, headache and muscle pain, and in the first two or three days even doctors can’t separate them from how you feel alone.

What does help is looking at the whole set of symptoms, the time of year and whether you have been bitten by mosquitoes. Dengue season on the island overlaps the second half of the year and the rainy months, and flu, COVID and RSV season overlaps those months too. That is why fall and winter bring so much confusion.

This guide does not replace a medical evaluation. It helps you decide what to do today, what to avoid taking, and when a fever stops being a video-visit problem and becomes an emergency-room problem.

These are clues, not a diagnosis. A person can have more than one infection, and symptoms vary from person to person.

With a cough, sore throat or congestion, think flu, COVID or another respiratory virus first. Dengue rarely causes marked cold symptoms, although a person with dengue can have a cold at the same time by coincidence.

With pain behind the eyes, a rash, nausea or vomiting and no cough, think dengue, especially if you were bitten by mosquitoes in the last 14 days or there are cases near your community. The mosquito that spreads it bites during the day and lives in and around homes.

With severe pain in the hands, wrists, knees or feet that makes it hard to move, think chikungunya. It is the joint pain that sets it apart, and in some people it can last for weeks.

With a sudden loss of taste or smell, COVID is more likely, though not everyone with COVID has it.

Two cautions: a rash also shows up with other infections and sometimes with medicine reactions, and the absence of one symptom never rules out an illness. The only way to confirm which is which is a test, which is why the doctor may order one.

Until dengue is ruled out, avoid aspirin and anti-inflammatories such as ibuprofen and naproxen, because the CDC says to avoid them in dengue. Read more in the guide to ibuprofen and naproxen. For fever and pain, the CDC recommends acetaminophen at the label dose; if you take other cold products, check that they don’t also contain acetaminophen so you don’t double up.

Rest and drink plenty of fluids, water or drinks with added electrolytes, to avoid dehydration. A fever makes you lose more fluid than usual, and with dengue, hydration is a central part of care.

To avoid passing it on at home: if it could be flu or COVID, stay home while you have a fever and wear a mask around others. If it could be dengue or chikungunya, prevent mosquito bites, because during the first week the virus is in your blood and a mosquito can pass it to someone else.

The right test depends on how many days you have had a fever. For dengue, the CDC recommends a molecular test (such as RT-PCR) or an NS1 antigen test in the first 7 days of symptoms, and IgM antibody testing from day 3. For flu and COVID-19, rapid and molecular tests exist, and COVID tests can also be done at home. For chikungunya, the CDC uses molecular and antibody tests depending on the day of illness.

No test is done in person during a video visit. If the doctor thinks a test would change what you should do, she gives you a lab order for a lab near you and goes over the result with you. A very early negative result does not always rule out an infection, and the doctor explains when to repeat it.

Influenza and COVID-19 are the only two on this list with specific antiviral medicines, and both work best when started early. For flu, the antiviral (such as oseltamivir) is by prescription and helps most when started within the first two days of symptoms. For COVID-19, antiviral pills are started within 5 days of symptoms in people at higher risk of severe illness.

The doctor assesses your case and your risk, and if appropriate, prescribes and we send your prescription to your pharmacy. Not everyone needs an antiviral, and not everyone receives one. Because of the deadline, if you have fever and body aches with cold symptoms, request a visit early: waiting to see if it passes can cost you the window when the medicine helps most.

For dengue and chikungunya there is no specific antiviral: care is rest, fluids and acetaminophen, and watching for warning signs.

If you have a fever and body aches and no warning signs, you see Dr. Diana Nieves Castro by video. She is a general practice physician licensed in Puerto Rico with several years of emergency-department experience, so she knows what can be managed at home and when you need to be seen in person. We evaluate, diagnose and treat; if needed, we give you a lab order.

The doctor goes over how many days you have had a fever, your other symptoms, whether you have had mosquito bites or contact with someone sick, your medicines and how well you are keeping fluids down. This is virtual urgent care for problems that are not emergencies, in English or Spanish, 24 hours a day, 7 days a week.

We see adults and children of all ages. For patients under 21, a parent or legal guardian stays on camera for the whole visit and shows photo ID. You need to be physically in Puerto Rico during the visit, and visitors are welcome.

Video doctor visits 24/7 — book online and choose your time right away.

A doctor visit has the same price for every age, with no membership. Your card is charged when you request the visit, and you get a full refund if the clinic can’t see you. A doctor's note after your visit is included at no extra charge. The service is run by The Health Initiative, a nonprofit. See pricing or book your visit.

In dengue, warning signs usually begin 24 to 48 hours after the fever has gone away, just when many people think they are recovering. In practice this falls between day 3 and day 7 of the illness. If you have or recently had a fever and notice any of these, go to an emergency room or call 911:

• Belly pain or tenderness
• Vomiting at least 3 times in 24 hours
• Bleeding from the nose or gums
• Vomiting blood, or blood in the stool
• Feeling extremely tired, restless or irritable

For flu, COVID and other respiratory infections, also go to the ER for trouble breathing, chest pain or pressure, blue lips or face, confusion, being unable to keep fluids down, or a fever that goes away and then returns along with a worse cough. Don't book a video visit for these signs: go straight to the emergency room.

People at higher risk (pregnant women, adults 65 and older, and people with heart or lung disease, diabetes or a weak immune system) should be seen early and watched more closely. In children, if your child is very drowsy or hard to wake, call 911. See also fever in children. Not sure whether you need the ER, urgent care or a video visit? Read ER vs urgent care in San Juan.