I've been suffering from the beasties for FOUR months now. Everything I have used (Lyclear, Nitty Gritty combing through with conditioner, rinsing with vinegar or Listerine - Orginal flavour!, leaving coconut oil overnight, blow-drying/straigtening hair) has been effective to a greater or lesser extent. IMO, Lyclear treatment (x3 with combing) has been LEAST effective, whilst the combing with conditioner daily and rinsing with Listerine seemed to dramatically reduce their numbers. The problem with lice is that the nymphs are sooooooo tiny that they can easily hide on clothing, bedding etc. and re-infect you. Contrary to what most internet sources say, the lice (even the baby nymphs) can live far longer than a few days off a human head. (I have deliberately kept a few on my dressing table mirror - they obviously fell off after a hair wash as I was blow-drying - and they have been running around in circles aimlessly for about a week at least! YUCK...but true! I could have mistaken them for specks of dust had it not been for them moving around quite quickly...
After experiencing indescribable frustration and upset, and doing extensive reading, research and conducting my own home experiments (involving essential oils and my microscope!), I have finally found a remedy which: a) works very effectively; b) is not expensive; and c) relatively kind to hair and scalp.
Head lice (especially the nymphs - young lice) are averse to particular essential oils. Those which I have found kill them on contact are Tea Tree Oil, Thyme (Thymus Vulgaris) and Eucalyptus. Appying 1 or 2 or ALL of these oils (about 6-8 drops) in a dilution of vegetable, olive or coconut oil (about 3-6 tablespoons or enough to soak through your hair) and leaving overnight (hair wrapped in shower cap with towel turban over top), seems to stop any scurrying lice in their tracks. Comb out the next morning then wash and rinse with shampoo with some more essential oil added. If possible blow-dry hair (lice hate intense heat too and are likely to fall off your head!).
Because of the lifecycle of the nits/lice, this treatment has to be repeated every 2 days for a week or two, though this is dependent on whether any viable nits (eggs) are still stuck in your hair and likely to hatch within the next week! The fact that you go to bed with your hair wrapped up also means you don't have to go crazy with washing bedding every day!
This is still a bit time intensive but had I found this remedy 4 months ago, I could have cleared the invasion of 6-legged visitors much more efficiently and effectively.
Good luck! Don't let the critters get you down!