Most so-called natural mosquito repellents do not last anywhere near as long as those containing synthetic chemicals, Consumer Reports found.
It's a big concern to people across the Americas as health officials caution everyone to avoid mosquito bites because of the spread of Zika virus, which causes severe birth defects and which sometimes also causes rare neurological complications in adults.
The consumer testing group released its latest update on which repellents work best Tuesday, and said those with naturally derived oils may smell nice, but they don't keep the mosquitoes off for long.
This jibes with what the Centers for Disease Control and Prevention advises. Both the CDC and Consumer Reports say that while "natural" sounds better and safer to consumer, it isn't necessarily so. That's especially true when it comes to mosquito repellents.
"Consumer Reports tested products to see which work best against the Aedes mosquitoes that spread Zika as well as against Culex mosquitoes, which spread West Nile, and the ticks that carry Lyme," the group says it its report.
"We looked at 16 repellents with a range of active ingredients, including conventional chemicals like DEET, synthetic plantlike compounds that resemble those found in nature, and plant oils like citronella and rosemary."
Their three top picks each contain a different synthetic chemical: DEET, picaridan or a derivative of eucalyptus:
- Sawyer Picaridin (20 percent picaridin),
- Ben's 30 Percent Deet Tick & Insect Wilderness Formula (30 percent DEET)
- Repel Lemon Eucalyptus (65 percent p-menthane-3,8-diol, a synthetic derivative of eucalyptus)
Once applied, they were able to ward off Aedes and Culex mosquitoes, plus ticks, for at least seven hours," Consumer Reports said.
The CDC says DEET is safe even for young children and pregnant women. It interferes with an insect's ability to sniff out a tender-skinned human victim.
The CDC notes insect repellents containing picaridin and oil of lemon eucalyptus "typically provide reasonably long-lasting protection." It cautions that products with oil of lemon eucalyptus should not to be used on children under 3. They can cause a painful rash.
"Five of the six plant-oil-based repellents we tested lasted an hour or less against Aedes mosquitoes, the kind than can spread Zika," Consumer Reports said.
The worst-performing product: EcoSmart Organic only kept mosquitoes away for half an hour.