You should worry about a mosquito bite and seek medical attention if you experience any of the following signs or symptoms:

• A wide area of redness around the bite or noticeable swelling beyond the usual small bump.
• A yellow, creamy discharge (pus) coming from the bite.
• Worsening pain and increased warmth at the site of the bite.
• Fever, chills, or flu-like symptoms such as headache, body aches, nausea, rash, or swollen lymph nodes developing a few days or weeks after the bite.
• Red streaks extending from the bite, which may indicate an infection spreading.
• Signs of a severe allergic reaction like hives, swelling of the throat, difficulty breathing, or anaphylaxis.
• If the bite causes extreme swelling, interferes with movement, vision, or eating.
• If you notice symptoms such as confusion, muscle weakness, or stiff neck.
• If the bite is accompanied by a high fever, severe headache, or signs of infection.

Other considerations include:

• Children and people with weakened immune systems might have more severe reactions.
• Some people may develop a rare allergic reaction called Skeeter syndrome, which involves severe local swelling, redness, and blistering that worsens over hours and may take up to 10 days to heal.
• Secondary infections from scratching can also be a cause for concern and may require antibiotic treatment.

If you notice any of these symptoms or your bite doesn't improve or worsens over several days, see a healthcare provider promptly. Preventing bites by using repellents with DEET or picaridin, wearing long clothing, and avoiding peak mosquito activity times (dusk to dawn) can help reduce risks.