Lice infestations can be frustrating, uncomfortable, and difficult to get rid of. When faced with a lice problem, using lice treatment shampoos often seems like the quickest and most effective solution. However, most lice shampoos contain pesticides and other chemicals meant to kill lice, and frequent use can lead to skin irritation, allergic reactions, and lice building up a resistance. Generally, lice shampoos are only meant to be used periodically as part of a complete lice treatment regimen.
What are lice shampoos?
Lice shampoos, also called pediculicides, are special medicated shampoos formulated to kill lice and their eggs (called nits). The most common active ingredients in lice shampoos include:
– Pyrethrins – Derived from chrysanthemum flowers, pyrethrins attack lice’s nervous systems.
– Permethrin – A synthetic version of pyrethrins that is longer-lasting.
– Malathion – An organophosphate that disrupts lice’s nervous systems.
– Spinosad – A bacteria-derived insecticide that causes paralysis and death in lice.
– Ivermectin – Interferes with lice’s nervous systems.
– Dimethicone – A silicone-based oil that coats lice and blocks their respiratory systems.
The chemicals in lice shampoos work by getting absorbed into the lice exoskeleton or respiratory system. This causes paralysis, inability to feed, and eventually death. The shampoos are generally left on the hair anywhere from 5-15 minutes to allow time for the active ingredients to work.
Are lice shampoos safe for everyday use?
Most health experts recommend against using lice shampoo every day or on a regular basis. Here are some key reasons why overuse can be problematic:
– Skin irritation – Lice shampoos contain harsh chemicals that can irritate the scalp, causing redness, dryness, flaking, burning, and itching if used too frequently.
– Allergic reactions – Some people may be allergic to ingredients like pyrethrins, malathion, and permethrin in lice shampoos and experience reactions like rash, swelling, and difficulty breathing when exposed.
– Hair damage – Overuse of lice shampoos can dry out the hair and scalp, leading to brittleness and breakage over time.
– Pesticide absorption – Daily exposure to pesticides found in lice shampoos may not be safe, especially for children. Long-term absorption risks are not known.
– Resistance – Using chemical shampoos too often can cause lice to develop resistance, making the products ineffective. This resistance is becoming more common.
– Not meant for prevention – Lice shampoos are designed to kill active lice infestations, not for lice prevention. Using when no lice are present is unnecessary.
– Off-label use – Using lice shampoo every day is considered off-label use and is not approved or recommended by health authorities or shampoo manufacturers.
For these reasons, it is best to use restraint with lice shampoos and reserve them only for periodic use as part of comprehensive lice treatment.
Frequency guidelines for lice shampoo use
Lice shampoo should only be used as directed – no more than 1-2 times per week for 1-3 weeks until lice and eggs are fully eradicated. Here are some general guidelines from health agencies for how often lice shampoos should be used:
| Lice Shampoo Brand | Recommended Frequency of Use |
| Rid | Every 7-9 days for 2 weeks |
| Nix | Every 7-10 days for 2 weeks |
| Vamousse | Once initially, repeat after 9 days if needed |
| Natroba | Once initially, repeat after 9 days if needed |
These lice shampoos are meant to be used in combination with thorough nit combing and cleaning of clothing, bedding, and other items that may contain lice or nits. Generally, a maximum of 3 applications or as directed by product instructions is sufficient.
Any more than this risks irritation, allergic reaction, lice resistance, and accumulation of pesticides on the scalp with unknown long-term effects.
What are some alternatives to daily lice shampoo use?
There are some alternatives that can be safer and gentler but still effective at managing or preventing lice without using conventional lice shampoo daily:
– Wet combing – Using a lice comb to mechanically remove lice and nits with conditioner and water every few days can disrupt the lice life cycle without chemicals. Takes patience but can be effective.
– Vinegar rinses – Rinsing hair in a 50/50 mix of vinegar and water may help repel lice without irritation from other chemicals. Can be done as often as daily.
– Tea tree oil shampoo – Contains natural lice-repelling compounds and can be used as regular shampoo. Exercise caution avoiding eyes.
– Salt and conditioner scrub – A mix of table salt and conditioner massaged into the scalp may help detach nits so they can be combed out. Can be done 1-2 times per week.
– Herbal shampoos – Some herbal shampoos like rosemary, lemon, and coconut oil have natural lice-deterring properties and can be used daily with low risk. Monitor for reactions.
– DIY essential oil sprays – Mixing a few drops of essential oils like lavender, eucalyptus, tea tree, and peppermint into a water/witch hazel spray can help repel lice between washings.
– Prescription ivermectin lotion – Applied every 7 days for 2 weeks, ivermectin lotion requires less frequent use than shampoos. Must be prescribed by a doctor.
While still not recommended for everyday prevention, these alternatives can help limit the use of pesticide lice shampoos to only when absolutely necessary for active infestations. Consulting with a doctor is also advisable when dealing with a difficult, recurring lice problem.
What are some possible negative side effects of using lice shampoo daily?
Overuse of lice shampoos can result in both mild and more severe negative side effects:
Mild side effects
– Dry, flaking, itchy scalp
– Irritated, red skin
– Increased dandruff
– Oilier hair and scalp
– Eye stinging if shampoo gets in eyes
– Tingling or numbness in hands after application (pyrethrins can be absorbed through skin)
– Unpleasant smell lingering on hair
– Hair discoloration or lightening
More severe side effects
– Hives, rash, or facial swelling
– Difficulty breathing
– Anaphylaxis, a life-threatening allergic reaction
– Hair loss
– Fever, chills, dizziness, headaches
– Nausea and vomiting
– Neurological effects like tremors, seizures, muscle cramps
– Increased absorption and accumulation of pesticides in blood and fatty tissues
Children and individuals with sensitive skin or asthma are at higher risk of adverse reactions to overusing lice shampoos. Any severe side effects require immediate medical care.
Conclusion
While lice shampoos are very effective for treating active head lice infestations, they should not be used daily or continuously to prevent lice. Doing so can frequently lead to skin irritation, allergic reactions, hair damage, and lice resistance while providing little added preventative benefit.
Lice shampoos should be used sparingly – no more than once every 7-10 days for no more than 2-3 weeks during an infestation. Proper combing, cleaning, and periodic use of alternative natural remedies are safer methods to deter lice between infestations. Consulting with a doctor to accurately diagnose lice and discuss treatment options is also wise.
With judicious use alongside comprehensive hygiene and combing techniques, lice shampoos can be a helpful tool to eliminate lice. But daily use should be avoided unless explicitly advised by a healthcare professional, as overuse causes more harm than good.
