Head Check Lice. Text us your lice photos and we will help you to determine what you have in your hair. In fact it takes 2-3 months of an active head lice infestation before there is even a chance of itching. Why is that? Because when lice feed on the human scalp, they leave behind a combination of saliva, anesthetic, and anticoagulant when they take a blood meal. And these substances do not initially cause an allergic reaction in humans.
However, after an extended period of time, and 50,000 – 100,000 head louse bites, a small percentage of people will develop an itchy scalp and/or an allergic rash on the back of the neck from the bites.
Head Check Lice. Do people always itch when they have Head Lice?
• No, people do not always itch when they have Head Lice.
• Most people don’t itch for the first 3 months when they have Head Lice.
• This makes sense from the Head Louse point of view.
• Head Lice do not want their host to know that they are setting up a Lice colony on their their head; until the Lice colony is well populated, and has sent out other Lice to other hosts to create satellite colonies.
• 3 months into the original Head Lice colony, a host can have an allergic reaction, which causes the itching.
• Head Lice leave saliva, anticoagulant, and anesthetic when feeding on a human host.
• All of these substances can trigger an allergic reaction to the bites.
Head Check Lice. What If I Am Itchy? The truth is that most of the itching associated with head lice is due to an unhappy scalp that has had pesticide lice shampoo applied to it. Just like with a mosquito bite, itching can last up to 2 weeks after the treatment. It still takes time for the histamine reaction of the lice feeding on scalp skin to settle down. Therefore, even after you have had lice treatment , the itching is just associated irritation.