Bug Bite Symptoms You Should Never Ignore

Most insect bites are relatively harmless, but some need medical attention. Learn to spot these signs of trouble.

a little girl observes bug bite on her upper arm

Medically reviewed in June 2022

Updated on June 8, 2022

With backyard barbeques, picnics, and summer hikes come bug bites—and quite often, lots of them. Some bites may go unnoticed, while others are so itchy and swollen you may be willing to try an array of over-the-counter remedies to get some relief.

That fact is, even seemingly harmless bug bites can lead to complications that may require medical attention. In other cases, insect bites and stings that aren’t dangerous for some people could trigger allergic reactions in others. Certain insects could also spread infections, such as Lyme disease, Zika virus, or Rocky Mountain spotted fever (RMSF) in parts of the United States and other locations around the world.

How do you know if your nagging bug bite is worth your concern? The answer depends on what bit you, how your body reacts to the bite, and whether or not it becomes infected, says Miriam Zylberglait, MD, an internist at HCA Florida Aventura Primary Care in Aventura, Florida.

“In general, bug bites are benign conditions,” says Dr. Zylberglait. “However, they may cause different types of complications, which could be as simple as a rash, but could also include more serious problems, like skin infections or allergic reactions.” 

What bit you?
Some bugs are stealthy. You might not realize that you’ve been bitten until it’s too late. In some cases, you may not even be sure what landed on your skin. A bug bite or sting usually isn’t cause for alarm, but there are situations that may require medical attention:

Ticks: If you find an engorged tick embedded in your skin, it may have been there a while. It can take a tick up to 2 hours to get ready to feed after planting itself on your skin, and it usually takes around 36 to 48 hours of feeding for them to transmit diseases such as Lyme disease.   

Not all ticks found in the U.S. carry diseases, but some blacklegged ticks can transmit infections. These include Lyme disease and anaplasmosis, an infection that is usually mild to moderate but in rare cases can be fatal. American dog ticks, Rocky Mountain wood ticks, and brown dog ticks can spread Rocky Mountain spotted fever, one of the deadliest tick-borne diseases in the U.S.

Ticks that spread these diseases are typically found in certain parts of the country, particularly the northeast or mid-Atlantic region and the north-central states (Minnesota, Wisconsin, and Michigan).

Most people with Lyme disease—roughly 70 to 80 percent—develop a bulls-eye rash, but not everyone will. Other signs of a tick-borne illness may include:

  • Chills
  • Joint or muscle aches
  • Swollen lymph nodes
  • Nausea
  • Vomiting
  • Stomach pain
  • Fever
  • Red or purple-spotted rash
  • Fatigue
  • Headaches

If blood tests confirm that you have Lyme disease, the bacterial infection can be effectively treated with antibiotics.

Lyme disease symptoms may go beyond the typical rash and can also affect your joints and long-term heart health if not appropriately treated,” says Zylberglait. Some of these longer-term issues could include muscle and joint pain, arthritis, memory problems, and nerve damage, depending on how far the disease has progressed. 

In most cases, early treatment of Rocky Mountain spotted fever and anaplasmosis with antibiotics can reduce the risk of serious complications. If left untreated, both can be life-threatening. 

Venomous spiders: Most spider bites are harmless and only result in some discoloration, swelling, or itchiness. Spider bites can often be treated by simply cleaning the area with mild soap and water and applying an antibiotic cream to prevent an infection. If you were bitten in the arm or leg, it might also be helpful to apply a cool, damp cloth to the area and keep it elevated. You may need antibiotics if the bite becomes infected (more on that later on).

Bites from black widow, brown recluse, and other venomous spiders, however, can trigger more serious reactions. You may not always be able to see what bit you, but if you do catch a glimpse, keep in mind that brown recluse spiders usually have a violin-shaped pattern on their body near their legs. Black widows have a large round body, with a red or orange hourglass marking on their underbelly. See a healthcare provider (HCP) if you have:

  • Pain and swelling that extends to your stomach, back, or chest
  • Stomach cramping
  • Sweating or chills
  • Nausea
  • Body aches
  • Dark blue or purple area toward the center of the bite that may turn into a large wound

If you’ve been bitten by a black widow, and you’re experiencing severe pain, your HCP may recommend an injection of antivenom—a medication that helps stop the effects of the toxins that have entered your body. In some cases, a brown recluse bite may cause an ulcer or lesion to form, which may require further medical treatment. It’s also important to see an HCP if you haven’t had a tetanus booster within the past five years.

Mosquitos: Certain mosquitos can spread infections, including West Nile Virus, Zika virus, dengue fever, and malaria. These infections aren’t as much of a concern in the U.S. as they are in other parts of the world, but they’re not completely out of the question.

In 2015 and 2016, there were major Zika virus outbreaks in the Americas, with widespread transmission of the virus in Puerto Rico and the U.S. Virgin Islands, along with limited local spread in Florida and Texas. Since 2018, no reported cases of Zika transmission by mosquitoes have occurred in the continental U.S., and no confirmed cases of Zika disease have occurred in the U.S. since 2019.  

If you’ve recently traveled to South America, the Caribbean, the South Pacific, Southeast Asia, Africa, and any other high-risk regions, watch out for possible warning signs of mosquito-borne diseases, such as:

  • Fever
  • Joint pain
  • Red and itchy eyes
  • Aches and pain
  • Nausea
  • Rash

“It’s very important for you to communicate to your physician that you were in any of these areas recently so that they can think through the proper diagnosis,” Zylberglait says.

There are not many specific treatment options for mosquito-borne illnesses, but acetaminophen can help reduce your fever. Your HCP may also advise you to stay hydrated and rest as much as possible. Malaria, caused by a parasite that infects red blood cells, requires specific drugs but treatment depends on which parasite is involved, as well as your age and symptoms. Treatment may also differ for women who are pregnant.

Every year, millions of people worldwide are infected with malaria, and hundreds of thousands die. Malaria transmission is most likely to occur in Africa, South America, and Asia, and is highest in sub-Saharan Africa and parts of the South Pacific. About 2,000 cases of malaria occur each year in the U.S., mostly in travelers from countries where transmission is more likely.

Other mosquito-borne diseases may lead to problems, as well. West Nile virus (WNV) is the leading cause of mosquito-borne illness in the continental U.S., according to the Centers for Disease Control and Prevention (CDC). Some people with West Nile virus may develop meningitis or encephalitis (inflammation of the brain). That may require additional treatment and a hospital stay involving intravenous fluid treatment, breathing support, or nursing care.

Outbreaks of dengue fever occasionally occur in the continental U.S., usually in travelers who were infected elsewhere, though it’s common in the U.S. territories of Puerto Rico, the U.S. Virgin Islands, and American Samoa. Severe dengue fever (sometimes called “breakbone” fever because it can cause very intense joint and bone pain) can cause internal bleeding and other complications. See an HCP immediately if you develop:

  • Stomach pain or tenderness
  • Persistent vomiting
  • Bleeding from nose or gums
  • Restlessness or irritability
  • Bloody stool or vomit

Recognizing allergic reactions
Like peanuts, dust, pollen, and other allergens, some people are allergic to specific bugs. Insects that can trigger allergic reactions include mosquitos, kissing bugs, bees, wasps, and fire ants. If you’re not allergic, a typical reaction may include pain, swelling, and redness or discoloration that’s confined to the sting or bite area. But if you’re having an allergic reaction, the symptoms may be more severe. Allergic reactions can cause:

  • Hives, itching, or swelling in areas beyond the sting site
  • Abdominal cramping
  • Vomiting, nausea, or diarrhea
  • Tightness in the chest or difficulty breathing
  • Swelling of the mouth, tongue, or throat
  • Difficulty swallowing

In severe cases, insect bites can trigger a life-threatening allergic reaction, called anaphylaxis. This is a medical emergency that requires immediate attention and treatment with epinephrine, corticosteroids, and antihistamines. Symptoms include difficulty breathing, dizziness, a sharp drop in blood pressure, loss of consciousness, or cardiac arrest (sudden loss of heart function). These usually occur within 5 to 30 minutes—and sometimes up to an hour—of getting bitten.

“While the bite might not look so dangerous and may be very benign for the majority of people, it could be very serious if you’re allergic,” says Zylberglait. “If you recognize these symptoms, you should seek help immediately.” And if your HCP has prescribed an epinephrine pen for allergic reactions, keep it with you at all times, so you can self-administer your medication when you need it.

Spot warning signs of infection
Regardless of the insect, a bite or sting could become infected if you scratch or pick at the area. Bacteria, such as streptococcus and staphylococcus epidermidis, are commonly found on the skin, Zylberglait explains. If left untreated, infected bug bites could lead to a deeper, more dangerous skin infection called cellulitis, which requires treatment with antibiotics. You should see an HCP as soon as possible if you have symptoms of cellulitis, such as:  

  • Fever
  • Chills
  • Swelling, discoloration, redness, or red streaking around the bite area
  • Cold sweats
  • Nausea
  • Trouble concentrating
  • Blisters, pus, or drainage
  • Swollen lymph nodes
  • An area that’s warm or painful to the touch

Prevention is best 
Avoid insect bites and stings with the help of protective clothing and repellents. Wear long-sleeved shirts and pants when possible, and tuck your pants into your socks to form an extra barrier.

It’s also important to plan ahead when traveling. Take extra precautions if you’re going to areas where mosquito- and tick-borne diseases are common. In some cases, your HCP may suggest receiving certain vaccines or taking preventive medications in preparation for your trip, Zylberglait notes.

And if you’ve had a previous allergic reaction to an insect bite, she adds, make sure you are familiar with any symptoms or red flags, in case it happens again.

Article sources open article sources

Centers for Disease Control and Prevention. How ticks spread disease. Page last reviewed: September 21, 2020.
Centers for Disease Control and Prevention. Prevent Lyme Disease. Page last reviewed: April 26, 2022.
Centers for Disease Control and Prevention. Signs and Symptoms of Untreated Lyme Disease. Page last reviewed: January 15, 2021.
Centers for Disease Control and Prevention. Anaplasmosis: Epidemiology and Statistics. Last reviewed August 6, 2021.
Centers for Disease Control and Prevention. Rocky Mountain Spotted Fever. Last reviewed May 7, 2019.
Centers for Disease Control and Prevention. Zika cases in the United States. Last reviewed December 22, 2021.
Centers for Disease Control and Prevention. Malaria. Last reviewed April 21, 2022.
Centers for Disease Control and Prevention. Where Malaria Occurs. Last reviewed April 9, 2020.
Centers for Disease Control and Prevention. About Malaria. Last reviewed February 2, 2022.
Centers for Disease Control and Prevention. West Nile virus. Page last reviewed: July 7, 2021.
Centers for Disease Control and Prevention. Dengue in the US States and Territories. Page last reviewed: October 7, 2020.

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