Triangle bites that may not be bed bug bites

Bites arranged in a line, cluster or triangle may reflect where an insect contacted the skin, how you slept or how separate spots became noticeable. Bed bugs are one possible cause, but fleas, mosquitoes, mites and other irritants can produce overlapping itchy bumps. A photograph cannot reliably identify the source by shape alone. Look for clues such as new marks after sleeping, affected household members, insects or specks around mattress seams, recent travel, pets and outdoor exposure. A rash from contact with a product can also resemble bites.

Avoid scratching, keep nails short and wash the area gently. A cool compress can reduce the urge to scratch. Check bedding, mattress seams, upholstered furniture and pet sleeping areas without spraying chemicals directly on skin. Photograph the marks with the date and note where you were, when they appeared and whether new spots are forming. If itching interferes with sleep, a clinician or pharmacist can advise whether oral antihistamine therapy or a topical corticosteroid is suitable; these options have different cautions and should be chosen for your situation.

Arrange medical advice if the marks keep appearing, spread, become painful or do not settle after removing a suspected exposure. Seek urgent care for facial or throat swelling, trouble breathing, faintness, rapidly worsening widespread hives or signs of infection such as increasing warmth, pus, fever or red streaking. A clinician can examine the skin and decide whether testing, treatment or pest-control advice is appropriate.

Ask: Could this be an insect bite, contact reaction or another rash? What features would make bed bugs more or less likely? Which treatment is appropriate if itching is disturbing sleep? How should I protect other household members while the cause is being checked?