To diagnose head lice, a healthcare professional may:

Examine the scalp and hair for lice, nits, or signs of infestation
Use a fine-toothed comb to check for lice and nits on wet hair strands
Look for nits using a magnifying lens or special light
Ask about symptoms and recent contacts to determine the source of infestation

Although head lice infestations are generally harmless, they can lead to some complications, such as:

Intense itching leading to skin infections from excessive scratching
Social and emotional distress, particularly among children
Temporary hair loss in severe infestations, although this is rare

There are a few common misconceptions about head lice that need to be clarified:

Head lice do not carry or transmit diseases.
Personal hygiene or cleanliness has no bearing on the likelihood of getting head lice.
Head lice cannot jump or fly; they can only crawl from one person to another through direct contact.

Other conditions that can cause itching and irritation of the scalp should be considered, including:

Dandruff or dry scalp
Allergic reactions to hair care products or certain ingredients
Scalp psoriasis or eczema