And the good news?
Most people don't need this stuff anyway. The vast majority of insect bites itch for a bit and go away on their own.
The best response usually is to do "the same thing that my parents did, which is nothing, or you could try a little bit of calamine lotion," said Misha Rosenbach, assistant professor of dermatology and internal medicine at the University of Pennsylvania.
Most bug bites are so minor that remedies have not been studied all that much, which is why the British reviewers found that official recommendations were often based on experts' advice without research to back them up.
"Just because there is no strong evidence doesn't mean that it doesn't work," Rosenbach said. "If one of my kids or I get a bug bite, I will put a topical steroid on it" to reduce inflammation. (Steroids such as Cortaid should not be applied to infected areas.)
There are many kinds of bugs, and many human responses, short-term and long.
Mosquitoes, bedbugs and fleas pierce the skin and inject anticoagulants to keep blood flowing, causing so little pain that they often go unnoticed. Horseflies and blackflies bite a bigger hole and lap up the blood, causing a bigger reaction. Bees, wasps and ants inject venom through a sting that can hurt.
Other than removing the stinger (quickly and without squeezing out more venom), treatment is largely the same: Wash the affected area with soap and water, and apply cold compresses to relieve the local pain.
Of course, there are exceptions. An infection - not just the crust that normally forms over the wound but pain, redness, warmth, and fever - calls for medical attention.
About 10 percent of people who get stung develop extreme redness and swelling at the site that emerges over one or two days and lasts five to 10 days, according to the Mayo Clinic. About 3 percent have a severe allergic reaction, known as anaphylaxis - skin reactions elsewhere on the body, difficulty breathing, swelling of the throat and tongue - that is potentially life-threatening. There is a 30 percent to 60 percent chance of a similar reaction the next time they get stung; an allergist may advise immunotherapy or prescribe an EpiPen.
Some serious illnesses will not show up immediately. Symptoms of West Nile virus, which is transmitted through a mosquito bite that looks like any other, will not appear for three to 14 days. Most people will not get sick at all. Up to 20 percent may have fever, headache, body aches, nausea, and vomiting; about one in 150 becomes severely ill with symptoms that include high fever, neck stiffness, muscle weakness, and tremors.
The "bull's eye" rash that may be a sign of Lyme disease is not apparent for three to 30 days after a bite from a deer tick. Nor are other symptoms such as fatigue, chills, fever, muscle and joint aches, and swollen lymph nodes.
The tick usually must remain lodged in the body for 24 hours to transmit the bacterium, so always check exposed areas after coming in from the brush; remove a tick carefully, without breaking off the head. If you think it has been in for a while, call a doctor immediately, as there is some evidence that postexposure prophylactic antibiotics can help if given soon.
Because a routine romp in the woods can attract dozens of bites, doctors really don't know how many turn serious.
"We only get to see the end-of-the-spectrum bug bites," said James R. Treat, a dermatologist at Children's Hospital of Philadelphia. Perhaps once a day, he said, the clinic sees children with swelling or "who are super itchy, with itchy bumps on the arms, face," and other exposed areas. A topical steroid prescribed by a doctor usually helps.
In most cases, however, "the main thing is not to do anything to make it worse," said Penn's Rosenbach. He often sees patients with a bug bite that still itches despite repeated use of an antihistamine like Benadryl.
"The problem," he said, "actually is the Benadryl."
Bug Bites in Brief
Children may be particularly bothered by insect bites.
Signs and symptoms
Mild reaction: Red bumps, itchiness, mild swelling.
Severe allergic reaction: Swelling of face or mouth, difficulty speaking, chest tightness, wheezing, dizziness, or fainting.
What to do
Mild reaction: If a stinger is visible, remove it as quickly as possible by scraping horizontally with a credit card or fingernail; wash with soap and water; apply ice or cool wet cloth for pain and swelling.
Severe reaction: Call 911; if child has injectable epinephrine, use it.
Also seek medical care if: Sting or bite is near the mouth; EpiPen was used; site looks infected (increasing redness, warmth, swelling, pain, or pus several hours after sting or bite).
SOURCE: Nemours Foundation
Guidelines, treatment, prevention, photos, singing bug games for children:www.philly.com/bugbites
Contact Don Sapatkin at 215-854-2617 or firstname.lastname@example.org.