Insect Bite

Is this your symptom?

  • Itching, pain, or swelling from an insect bite

Some Basics...

  • There are many types of insects that can bite people.
  • In most cases, insect bites only cause a minor reaction at the bite site. These bites can be treated at home.
  • More serious reactions can happen to people who are allergic to insect bites. Serious reactions are medical emergencies.
  • Scratching at a bite only irritates the area even more. It is the saliva the insect leaves behind that makes the itchy bump. Scratching at it can make it worse. So, try not to scratch!
  • A tetanus shot is not needed after an insect bite.

Types of Insect Bites

  • Itchy Insect Bites: Some insect bites cause itchy, red bumps. These include mosquitoes, chiggers (harvest mites), fleas, and bed bugs.
  • Painful Insect Bites: Some insect bites cause painful red bumps or blisters. These include horseflies, black flies, deer flies, gnats, harvester ants, blister beetles, and centipedes. Within a few hours, fire ant bites can change to blisters or pimples.

What are No-See-Ums?

  • No-see-ums are tiny bugs that are about 1/10 - 1/15 of an inch (0.16 - 0.25 cm). They are so small that they can fly through normal screens. They are most active at dawn or at dusk. They are attracted to light.
  • Other names: They are also called biting midges, sand gnats, punkies, and granny nippers.
  • Where They Live: They are found near water where the sand or dirt is wet. They can live by rivers and ponds, ocean beaches and salt marshes. They are also found in puddles by fields or construction sites.
  • How They Bite: Like the mosquito, only the female bites. She is actually sucking blood. She needs blood proteins to make her eggs. The males often fly to where the females are feeding in order to mate.
  • Symptoms: The bite is often painless or there may be a faint sting for just a second. Within 12 hours the bite mark becomes a small red spot. It will become extremely itchy. The spot can last 5-7 days. Some people can have a larger reaction. No-see-ums often fly in swarms. So a person can get bitten many times and have lots of itchy red spots.
  • Over-the-Counter (OTC) Treatment for Itching: Hydrocortisone cream may help. Antihistamine drugs like Benadryl can help with the itching.
  • Prevention: They do not bite through clothes. Wear long sleeves and long pants, socks and shoes to prevent bites. An insect repellent made with DEET can also help. Smaller mesh for window screens can keep them out. They are not good fliers, and can't fly in a strong wind. Fans can help blow them away.

What are Chiggers?

  • Chiggers are the larvae form of a type of mite. These are very tiny bugs that are about 1/150 of an inch (.017 cm). They are too small to be seen.
  • Other Names: They are also called red bugs, harvest mites, or jiggers.
  • Where They Live: They are found in tall grass and brush.
  • How They Bite: A chigger can get onto the skin or clothing when a person walks past. It crawls along the person's body looking for a spot to feed. The chigger attaches to the skin. It then begins to suck out fluids. When it is full, it drops off to the ground. Chigger bites are often found around the waist. This is because the tight waistband stops them from crawling farther.
  • Symptoms: Severe itching is the most common symptom. This is often the worst 1-2 days after the bite. There may also be tiny red bumps or small hives. Itching and redness may last 1-3 weeks.
  • OTC Treatment: Hydrocortisone cream may help. Antihistamine drugs help with the itching. Chiggers do not burrow under the skin. Putting nail polish onto the bites does not help.
  • Prevention: Wash with soap and water after being outdoors. This can help remove chiggers that have not attached yet. Wear long pants, socks and shoes when hiking. Change clothes when you come inside. Insect repellant with DEET also seems to help prevent bites.

What are Bed Bugs?

  • Bed bugs are small, visible, blood-sucking bugs. They are about ¼ an inch (7 mm) in length.
  • Where They Live: During the day they hide in mattresses, beds, floors, and walls. At night, they come out of hiding and bite humans. Bed bugs are found worldwide.
  • Symptoms: There is no pain while the bed bug is biting. Small red bumps or large itchy wheals (2-20 cm) may later appear. Blisters can form on the bite site.
  • OTC Treatment: Hydrocortisone cream and antihistamine drugs help with the itching. Watch for signs of infection.
  • Prevention: Avoid hotels and hostels where bed bugs have been found. Check along corners of bedding or mattresses for these bugs. Wash linens once a week in hot water. Insect repellents such as DEET (used on the skin) and permethrin (used on clothing) do not prevent bed bug bites.

When to Call for Insect Bite

Call 911 Now

  • Passed out (fainted)
  • Trouble waking up or acting confused
  • Trouble breathing or wheezing
  • Hoarseness, cough, or tightness in the throat or chest
  • Swollen tongue or trouble swallowing
  • Past severe allergic reaction to the same insect bite (not just hives or swelling)
  • You think you have a life-threatening emergency

Call Doctor Now or Go to ER

  • Hives or swelling all over the body
  • Severe bite pain that is not better 2 hours after pain medicine
  • Redness and sting site is tender to touch and have a fever
  • You feel weak or very sick
  • You think you need to be seen, and the problem is urgent

Call Doctor Within 24 Hours

  • Sting site is red or very tender to touch and this started over 24 hours after the bite
  • Sting site is red or very tender to touch and it is getting larger over 48 hours after the bite
  • You think you need to be seen, but the problem is not urgent

Call Doctor During Office Hours

  • Scab drains pus or gets bigger and is not better after using antibiotic ointment for 2 days
  • You have other questions or concerns

Self Care at Home

  • Normal insect bite
  • Scab drains pus or gets bigger in size

Care Advice

Treatment for Insect Bites

  1. What You Should Know:
    • In most cases, insect bites only cause a minor reaction at the bite site.
    • Scratching at a bite only irritates the area even more. It is the saliva the insect leaves behind that makes the itchy bump. Scratching at it can make it worse. So, try not to scratch!
    • You can treat minor reactions at the bite site at home.
    • Here is some care advice that should help.
  2. Treating Itchy Insect Bites:
    • Put calamine lotion or a baking soda paste on the bite.
    • If the itch is severe, put on 1% hydrocortisone cream. Do this 4 times a day until it is less itchy. Then switch to calamine lotion.
    • Try putting firm, sharp, steady pressure on the bite for 10 seconds. A fingernail, pen cap, or other object can be used.
  3. Antihistamine Medicine for Severe Itching:
    • You can take one of the following drugs for severe itching: diphenhydramine (Benadryl), cetirizine (Zyrtec), or loratadine (Claritin, Alavert).
    • They are over-the-counter (OTC) drugs. You can buy them at the drugstore.
    • Use the lowest amount of a drug that makes your itching feel better.
    • Diphenhydramine (Benadryl) may make you feel drowsy. Loratadine and cetirizine do not cause you to feel as sleepy. They are also long-acting so they last 24 hours.
    • Read the instructions and warnings on the package insert for all medicines you take.
  4. Treating Painful Insect Bites:
    • Rub the bite with a cotton ball soaked in a baking soda solution. Do this for 15 to 20 minutes. This will most often help with the pain. Do not use near the eye.
    • Another choice is to put an ice cube on the bite for 20 minutes.
  5. Pain Medicine:
    • You can take one of the following drugs if you have pain: acetaminophen (Tylenol), ibuprofen (Advil, Motrin), or naproxen (Aleve).
    • They are over-the-counter (OTC) pain drugs. You can buy them at the drugstore.
    • Use the lowest amount of a drug that makes your pain feel better.
    • Acetaminophen is safer than ibuprofen or naproxen in people over 65 years old.
    • Read the instructions and warnings on the package insert for all medicines you take.
  6. What to Expect:
    • Most insect bites itch or hurt for 1-2 days.
    • The swelling may last a week.
  7. Call Your Doctor If:
    • Severe pain lasts more than 2 hours after pain medicine
    • Infected scab is not better after 48 hours of antibiotic ointment
    • Bite looks infected (redness, red streaks, or is tender to touch)
    • You think you need to be seen
    • You get worse

Infected Sore or Scab

  1. What You Should Know:
    • Sometimes an insect bite can get infected a couple days after the bite. An infection does not start in the first 1-2 days.
    • Signs of an infection are redness, tenderness to touch, and a scab that does not go away. An infected sore is often covered by a soft, 'honey-yellow,' or yellow-brown crust or scab. Sometimes the scab may drain a tiny amount pus or yellow fluid. If there is pain, it is mild.
    • These sores should get better with daily cleaning and antibiotic ointment.
    • You can treat a minor infection of an insect bite at home.
    • Here is some care advice that should help.
  2. Cleaning:
    • Wash the bite 2 to 3 times daily with antibacterial soap and warm water.
    • Gently remove any scab. The bacteria live under the scab. You may need to soak the scab off. Do this by placing a warm wet washcloth on the sore for 10 minutes. You can also use gauze.
  3. Antibiotic Ointment:
    • Put an antibiotic ointment on the sore 3 times per day.
    • Cover the sore with an adhesive bandage (Band-Aid) to avoid scratching and spreading.
    • Use Bacitracin ointment (OTC in the United States) or Polysporin ointment (OTC in Canada). You can also use one that you have.
  4. Avoid Picking: Avoid scratching and picking. This can worsen and spread a skin infection.
  5. How It Is Spread:
    • Infected sores can be spread by skin to skin contact.
    • Wash your hands often and avoid touching the sore.
    • Work and School: You can go if the sore is covered.
    • Sports: You need to get antibiotic treatment for 3 days before you can play. There can be no pus or drainage. You should check with your trainer, if there is one for your sports team.
  6. What to Expect:
    • The sore should stop growing in 1-2 days. It should start to get better within 2 to 3 days.
    • The sore should be healed in 7-10 days.
  7. Call Your Doctor If:
    • Have a fever
    • Spreading redness or a red streak
    • Sore gets bigger
    • Sore is not better after using antibiotic ointment for 2 days
    • Sore is not healed in 7 days (1 week)
    • New sore appears
    • You think you need to be seen
    • You get worse

Preventing Insect Bites

  1. Prevention:
    • Wear long pants and long-sleeved shirts.
    • Avoid being outside when the insect is most active. Many insects that cause itchy bites are most active at sunrise or sunset. These include Chiggers, No-See-Ums, and Mosquitoes.
    • Insect repellents with DEET in them work well to prevent many itchy insect bites.
  2. DEET:
    • DEET is a very strong insect repellent. It also repels ticks.
    • Higher strength DEET works better. All DEET over 50% works the same. For children and teens, the American Academy of Pediatrics recommends a maximum strength of 30%. Health Canada recommends using a strength of 5-30% for adults.
    • Spray on exposed areas of skin. Do not put near your eyes, mouth or any irritated skin. Do not put it on skin that is covered by clothing.
    • Always wash it off with soap and water when you return indoors.
    • DEET can damage clothing made of synthetic fibers, plastics, and leather.
    • Women that are breastfeeding may use DEET. No problems have been found.
    • Read all label instructions.
  3. Picaridin (KBR 3023):
    • Research shows that it works just as well as DEET.
    • It has been used in other countries for years.
    • Read all label instructions.
  4. Permethrin - An Insect Repellent for your Clothing and Gear:
    • Products with permethrin in them are very strong mosquito repellents. These include Duranon, Permanone, and Congo Creek Tick Spray. They also repel ticks. You put permethrin on your clothing instead of your skin.
    • Spray it on your clothes before you put them on. You can also put it on other outdoor items (shoes, mosquito screen, sleeping bags).
    • It continues to work even after your clothes are washed several times.
    • Do not put this type of repellent on your skin.
    • Read and follow the package directions carefully.
  5. Call Your Doctor If:
    • You have more questions
    • You think you need to be seen
    • You get worse

West Nile Virus (WNV) Information

  1. Symptoms of WNV:
    • No clinical symptoms: 80% of WNV cases.
    • Mild febrile illness: 20% of WNV cases. Symptoms include fever, headache, body aches, and sometimes a skin rash. These last 3-6 days and go away without any treatment. This is also called WNV fever.
    • Encephalitis or viral meningitis: 0.7% of WNV cases. Symptoms are high fever, stiff neck, confusion, coma, convulsions, muscle weakness, or paralysis. The muscle weakness is often on one side of your body. These symptoms are easy to see.
    • Fatal: 10% of those who are hospitalized will die.
    • Pediatric cases are most often mild. Most encephalitis and deaths happen to people over age 60.
  2. Diagnosis of WNV:
    • Mild cases do not need to be diagnosed.
    • Severe cases (with encephalitis and viral meningitis) will be hospitalized based on their symptoms. The disease is diagnosed by tests on the blood and spinal fluid. These tests are not used for the normal mild infections seen with this virus.
  3. Treatment of WNV:
    • No special treatment is needed after a mosquito bite.
    • There is no anti-viral agent for WNV.
    • WNV patients in the hospital are given IV fluids, airway control, and care.
    • There is no vaccine that can prevent WNV in humans.
  4. How WNV Is Spread:
    • The West Nile virus is spread by the bite of a mosquito. The virus comes from infected birds.
    • Even in an area with WNV, less than 1% of mosquitoes carry it.
    • The virus is spread from mosquito-to-human.
    • You cannot spread WNV to other people. It is not spread by kissing, touching, sex, or sharing glassware.
    • Mothers with mosquito bites can keep breastfeeding.
    • Symptoms will show 3-14 days after the mosquito bite.
  5. Call Your Doctor If:
    • You have more questions
    • You think you need to be seen
    • You get worse

And remember, contact your doctor if you develop any of the 'Call Your Doctor' symptoms.

Disclaimer: This information is not intended to be a substitute for professional medical advice. It is provided for educational purposes only. You assume full responsibility for how you choose to use this information.


Last Reviewed: 12/11/2017 1:32:05 AM
Last Updated: 5/17/2017 5:42:35 PM

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Female Mosquito

The photo shows a female mosquito feeding on a human host.

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