 DEET has been considered the most effective mosquito repellent. Unquestionably, read this editorial in the Journal of Family Practice, it should be the only mosquito repellent recommended by physicians with no other repellent coming close. Given the dramatic efficacy, it's hard to concede that any other repellent would ever beat it. However, there are some rare reports of severe reactions to DEET, not to mention the fact that it can melt plastics like eyeglass frames and cell phone components, and many consumers find the odor and sensation on the skin unpleasant. Enter picaridin. Overall, studies have shown little difference between DEET and picaridin applied at the same dosage, with some evidence pointing to a superior persistence for picaridin, all without the iridistancy, odor, and melted glasses. No wonder it got consumer reports pick for the best overall insect repellent. Note that concentration matters—their 20% picaridin product top the list, but at 5% it was one of the worst-performing products. Any toxicity? Adverse effects, when occurring, primarily manifested as eye irritation, redness, vomiting, and oral irritation. But of course you're not supposed to eat it or spray it in your eyes, but even unintentional ingestion was associated only with relatively minor toxicity. What about the electronic mosquito repellent gizmos? Ten studies done in all ten found that there was no difference in the number of mosquitoes landing on people with or without the gizmos, and experiments out in the field confirm no effect on preventing mosquito bites. Picaridin was roughly based on a black pepper compound, but like DEET is a synthetic chemical. Are there any natural repellents? Of course, just because something is natural doesn't mean it's necessarily safe. Strict 9 is a natural product of the Strict 9 tree, and ricin from caster beans is 10,000 times deadlier still. In fact, the top 10 most toxic poisons are all natural. But let's look at the mosquito repellent effects of about 20 essential oils compared to a placebo control group and to DEET. The asterisks point to the significant result, so here's a cleaner peek. As you can see, only five had any lasting effect at all. Peppermint and lemongrass oil were effective for 30 minutes. Spearmint and garlic oil started working, but didn't even last that long. Cinnamon oil, though, reduced mosquito attraction for one and a half hours. The remaining essential oils had no significant effect on mosquito attraction at any time point, and this includes citronella. Citronella was the most widely used repellent before DEET was invented, and it's still used today in many formulations despite inferior efficacy. At lower concentrations, it may only last a few minutes, and at higher concentrations, citronella can cause skin irritation. Compared to a complete protection time of six hours for DEET, citronella may only last 10 and a half minutes. Therefore, citronella may be acceptable for brief exposure to nuisance mosquitoes, but it is not advised for protection if you really can't afford to get bit. Essential oils, read this, family medicine journal editorial, have no effectiveness and are not recommended. But that was before we learned about lemon eucalyptus, the only plant-based repellent recommended by the CDC, though should not be used by pregnant women or children younger than three years of age. Consumer Reports listed it as one of their top three picks warding off mosquitoes and ticks for at least seven hours. All the other botanical products they tested failed, but 40% lemon eucalyptus was shown to prevent bites for 47 hours after application for aggressive species of mosquitoes and for greater than 12 hours for less aggressive mosquitoes. A period of prevention greater than at least a 10% DEET repellent.