Mosquito repellent and prevention in Puerto Rico: dengue, Zika and chikungunya

According to the CDC, dengue, Zika and chikungunya spread through the bites of infected Aedes mosquitoes (Aedes aegypti and Aedes albopictus). No medicine cures these infections; treatment is supportive, so the best protection is avoiding the bite. We have guides to the symptoms and warning signs of dengue, Zika and chikungunya.

Aedes mosquitoes live close to people, inside and around the home, and lay their eggs in clean water that sits still in small containers. According to the CDC, they bite during the day, with activity often highest in the early morning and late afternoon, but they can also bite at night, especially in lit areas. That is why a bed net helps but is not enough on its own.

Choose an EPA-registered repellent. That means the agency evaluated the product for safety and effectiveness when used as the label directs. According to the CDC and the EPA, the active ingredients recommended for repelling mosquitoes are:

The EPA has an online tool to search for repellents by how long you need protection and by active ingredient (search for the "EPA repellent search tool"). If you are unsure which product suits you, you can ask the doctor by video. Read the label: it tells you how long the product protects and how to apply it. A higher percentage of active ingredient protects for longer; it does not repel more strongly.

“Natural” repellents that are not EPA-registered have not been evaluated the same way, so we cannot rely on them to protect you from these diseases. We also know of no solid evidence that wristbands, ultrasonic devices or scented candles protect. We do not recommend brands in this guide.

According to the CDC and the EPA, always follow the directions on the product label. In general:

According to the CDC, EPA-registered repellents are safe for pregnant and breastfeeding women when used as the label directs. Because Zika and dengue during pregnancy can be serious, the CDC advises not skipping them. If you are pregnant, any decision about testing or follow-up belongs to your obstetric provider; we do not provide pregnancy care.

Repellent is only one part of protection. According to the CDC:

Aedes mosquitoes lay their eggs in water that sits still, and the eggs can survive dry for months until it rains again. The rainy season and the weeks after a hurricane or storm are higher-risk times, because rain fills containers in the yard and on the roof. According to the CDC, once a week empty, scrub, turn over, cover or throw out containers that hold water.

Check these places: buckets and pails, old tires, saucers under plant pots, pet water bowls, vases, cans and bottles, clogged roof gutters, toys in the yard, tarps or awnings that collect water, and the base of bromeliads or other plants that hold water. Water tanks and cisterns should have tight-fitting lids and screening over any openings.

After a hurricane, water outages lead many families to store water in containers; keep them covered. For other health risks after a hurricane, such as contaminated water, heat and injuries, read health after a hurricane. If you were in floodwater and have a fever, see our leptospirosis guide.

If you see breeding sites in a public place or on an abandoned lot, you can report them to your municipality or the Department of Health.

Most mosquito bites only cause an itchy bump that goes away in a few days. Wash the area with soap and water, use cold compresses, and avoid scratching so you do not break the skin. An over-the-counter hydrocortisone cream or an oral antihistamine can ease the itch, as the label directs. For more detail, see bug bites.

If the area becomes warm, red, swollen or has pus, or the redness spreads, it may be infected and is worth having the doctor look at by video.

A bite does not cause a fever by itself. If, in the days or weeks after bites, you have a fever, headache, pain behind the eyes, muscle or joint pain, a rash or red eyes, it could be dengue, chikungunya, Zika or another infection. Only a lab test can tell them apart.

Dr. Diana Nieves Castro, a Puerto Rico–licensed general practice physician with several years of emergency-department experience, can see you by video. We evaluate, diagnose and treat; if needed, we give you a blood test order for a lab near you. See also our fever guide.

Until dengue is ruled out, the CDC says to avoid aspirin and other anti-inflammatory medicines (such as ibuprofen) because of the risk of bleeding; acetaminophen, rest and fluids are used for fever and pain. If appropriate, the doctor prescribes and we send your prescription to your pharmacy.

We see adults and children of all ages; for patients under 21, a parent or legal guardian stays on camera for the whole visit with photo ID. You need to be physically in Puerto Rico during the visit. Visiting? See our care for visitors.

A doctor visit has the same price for every age, with no membership. Video doctor visits 24/7 — book online and choose your time right away. Your card is charged when you request it, and you get a full refund if the clinic can’t see you. We send you a secure video link that works on your phone, tablet or computer. The service is run by The Health Initiative, a nonprofit. Book your visit.

For your safety, with any of these signs call 911 or go to an emergency room, and don’t book a video visit. See when to go to the ER.