Bug bites 101: When to call a doctor

June 14, 2022

Mark L. Friedman, MD, FACEP, FACP

Bug bites: They itch, they're an eyesore, and always have you asking, "Does this look normal?" 

The first step is to figure out what bit you. If it was a flying or buzzing insect, it was likely a mosquito or fly. If the sting was sudden and painful, that's a bee or a wasp. Did you find a tick attached to your skin? How about physically see a spider bite you? Perhaps it's even a rash or wound that occurred for no apparent reason. 

Here are the most common biting bugs and what to watch for. As always, if you are having trouble breathing after a bug bite, call 911 or go to the emergency room. 


North American mosquitoes are generally harmless, but can sometimes carry diseases, including West Nile virus. In tropical climates (Africa, Central and South America), mosquitoes can carry malaria, Zika virus, yellow fever, and other nasty diseases. 

When to call a doctor

Call a doctor if you experience the following symptoms, which could be signs of a mosquito-borne illness:

  • Fever
  • Headache
  • Body aches
  • Skin rash
  • Swollen lymph nodes

Treating mosquito bites

Scratching mosquito bites might seem like a solution for your itch, but it's actually the opposite — and might create an open wound, which could lead to infection. Topical hydrocortisone (OTC) cream or a prescription steroid cream along with an antihistamine can help with the itching.


Bees and Wasps

When bees and wasps are startled, they may see you as a threat and react with a sting. So, leaving them alone is a good place to start.

"What stung me?"

If you're stung by a bee, it'll leave behind its stinger, which should be visible. On the other hand, wasps (which include yellow jackets), usually just leave you with sudden pain and a small, red bump. 

What to watch for

Some allergic reactions to stings can be severe, so if you experience shortness of breath, or any of the following symptoms, call 911 immediately. 

  • Difficulty breathing
  • Swelling of the face or throat
  • Fever
  • Nausea
  • Convulsions
  • Vomiting
  • Prior history of severe reaction to stings

Treating bee and wasp stings

Apply ice or a cool compress to the sting. Take an antihistamine (like Benadryl). If you have been prescribed an EpiPen injector due to previous severe reactions, use it! Milder reactions do not usually require a trip to the ER, but you should still call a doctor to discuss your symptoms and next steps. Multiple stings (any more than five) require immediate medical attention. 


"Spider bites" are relatively rare events. They can appear much larger and itch much more than mosquito bites. 

When to call a doctor

Spider bites can result in itching and red bumps, a lot like a mosquito bite. The only dangerous North American spiders are the Black Widow and Brown Recluse. These bites can cause painful and obvious signs:

  • Severe and local pain
  • Cramping
  • Ulcers or puss
  • Necrotic wound

Call a First Stop Health doctor right away if you suspect a Black Widow bite or show any of the symptoms above. 



Ticks are common in forested or grassy areas and can latch on quickly to bare skin. Ticks can carry a variety of illnesses, the most common of which is Lyme disease. Lyme disease is a bacterial illness spread through the bite of an infected black-legged tick, also known as a deer tick. 

How to prevent tick bites

To reduce your risk of Lyme disease and other tick-borne illnesses:

  • Stay out of tick-prone (brushy or wooded) areas
  • Have your yard professionally sprayed annually (if you live in an endemic zone)
  • Wear long sleeves and long pants outdoors
  • Spray your shoes, pants, and socks with permethrin (not while you are wearing them) and let them dry before wearing 
  • Spray your skin with 20% DEET (not for small children)
  • Search your skin for ticks after being outside
  • Use tweezers to carefully remove ticks (without squeezing) if found on your skin. Save the tick (in a sealed plastic bag or jar) for identification and possible testing. 

Tick bites start as a small, red flat rash. Unlike a mosquito bite, they do not itch.

When to call a doctor

Talk to a First Stop Health doctor if you develop:

  • An expanding red rash that may have a "bull's eye" center, like the logo for Target
  • Fever
  • Chills
  • Extreme fatigue

Lyme disease can cause severe and long-lasting symptoms if treatment is delayed. If caught early, however, it can be treated. Other tick-borne illnesses, including Babesiosis, Powassan fever, and Rocky Mountain spotted fever, can be serious as well. A First Stop Health doctor visit can diagnose and begin treatment of tick-borne diseases.


Fleas, Bed Bugs, and Chiggers

Any of these bites will feel itchy, but are usually harmless. These insects don't normally carry diseases (rarely, fleas can carry plague, mainly in the desert southwest and great plains), but scratching can cause infection. If you exhibit puss, swelling, or signs of local infection, call a First Stop Health doctor. 

Bed bugs are a common nuisance and can be identified by the reddish-brown stains they leave on mattresses and bed sheets. Adult bed bugs are about the size and color of an apple seed. Their bites are small, red and itchy, and often appear in a line. They are typically first noticed upon waking up in the morning. Bed bugs can easily spread by latching onto clothing and traveling to other homes, office lounges, or shared school cubbies. If you suspect bed bugs, research the rash and their removal here.

When to call a doctor

The good news is that bed bugs don't carry disease. In rare cases, they may cause an allergic reaction. Call a doctor if you experience:

  • Enlarged bite marks
  • Painful swelling

Talk to a Doctor 24/7

Do you or your kid have a nasty-looking bite? Are you showing some of the signs above? Our doctors are always here and can advise you immediately on next steps. 

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Originally published Jun 14, 2022 12:00:00 PM.