Can Bug Bites Make You Sick?

Bug bites can cause itchiness, red skin bumps, some swelling and sometimes a sharp, immediate pain. While all these side effects are unpleasant, they are normal reactions to bug bites. In most cases, you can treat bug bites at home with a pain reliever, an anti-inflammatory medication or hydrocortisone cream. However, certain bug bites can make you sick and may need medical attention.

If you get one of these kinds of bug bites followed by any of these symptoms, seek medical care.

• Mosquito bites: Five to 15 days after the bite, watch for headache, fever or swollen glands (lymph nodes).
• Bed bug bites: One to three days after a bite, monitor for symptoms of an allergic reaction such as hives, itching or swelling at the bite site; abdominal pain, cramping or nausea; tightness of the chest or difficulty breathing; trouble swallowing or swelling of the tongue.
• Spider bites: Your bite may be poisonous if you feel pain and swelling within 30 to 40 minutes after the bite, or if you experience muscle rigidity, stomach and back pain, nausea, vomiting and breathing difficulties within eight hours. Tightness in the chest and problems breathing or swallowing may be signs of an allergic reaction.
• Tick bites: Fever, headache, muscle or joint aches, and fatigue can be a cause for concern. A bull's-eye rash or a pattern of rings appearing up to a month after the bite may be a sign of Lyme disease. A skin rash that begins on the ankles and wrists and spreads to the rest of the body could be a sign of Rocky Mountain spotted fever.

Do You Need DEET?

A good repellent is essential for protecting your skin from bug bites. Diethyltoluamide (DEET) is the most commonly used chemical in insect repellents. The amount of DEET in your insect repellent matters. The percentage should be high enough to protect (the more DEET, the longer it lasts) but not so high that it causes skin irritation, which is a particular concern for children. Look for a bug spray containing 20% to 30% DEET. According to the Environmental Protection Agency (EPA), DEET is approved for use on children of all ages.

Most natural ingredients are not as effective as (DEET), but you can still pick a safe, environmentally friendly option certified by the EPA. To find out if an insect repellent is certified, look for an EPA registration number (EPA Reg No.) on the product label. This number means that the manufacturer provided the EPA with technical information on the effectiveness of the product. The Centers for Disease Control and Prevention recommends the use of products registered by the EPA.

Insect-repelling candles, diffusers, mosquito coils and mosquito sticks are also popular options for a patio or campsite in low-wind conditions.

Be particularly careful from dusk to dawn when many bugs, particularly mosquitoes, are most likely to bite.

When to Reapply Insect Repellent

Like sunscreen, insect repellent needs to be reapplied regularly to remain effective. Reapplying every few hours is a reliable strategy, but the specific frequency depends on the active ingredient and its percentage.

• Repellents with DEET can last eight to 10 hours.
• Picaridin, another chemical option, lasts up to eight hours.
• Synthesized plant oils like EPA-certified lemon eucalyptus oil or IR3535 usually last anywhere from four to eight hours.
• A completely natural repellent, such as essential oils from plants, may need to be reapplied as often as every 30 minutes.

No matter what type of insect repellent you use, always read and follow label directions.

Find a Northwestern Medicine Immediate Care Center.