The CDC estimates nearly 12 million cases of lice in the US each year. To ensure the efficacy and transparency of our products in this ongoing epidemic, Mayday sponsors independent studies of our proprietary formulas.
“Mayday shampoo kills over 99% of head lice without the use of harmful pesticides or toxins.”
Independent Lab Studies
CONDUCTED 2024 & 2025
The Methodology
Collection
Freshly harvested head lice were donated by willing individuals. Studies commenced within 30 minutes of separation from the host.
Comparison
MAYDAY products were tested in vitro against generic alternatives and the leading lice treatment (Rid), across our 2024 and 2025 studies.
Analysis
Lice were monitored after exposure to determine if and when viability was compromised. In 2025, DNA testing confirmed they were pesticide-resistant super lice.
The Results
Kills Lice and Nits
MAYDAY Lice Prevention Shampoo was 99.05% effective at killing head lice and nits in independent lab testing.
Stuns and Repels
MAYDAY Lice Fighting Conditioner stunned and repelled head lice 95.24% of the time.
Treats Active Lice
MAYDAY Lice Treatment was 79% effective at killing head lice — nearly double the leading treatment (Rid) at 44%.
Super Lice Confirmed. MAYDAY Still Kills Them.
Our 2025 study confirmed through DNA testing at Seoul National University that 100% of the lice tested carried the kdr pesticide-resistance mutation — verified, pesticide-resistant “super lice.” MAYDAY products were proven effective against them.
100%
Reformulated Shampoo mortality against super lice (reported as 99%)
100%
Treatment Hair Solution mortality against super lice
97%
Detangler Spray stun & repel against super lice and lice
92%
Furniture & Bedding Spray killing lice — also effective on bed bugs
Three-phase, four-arm study with super lice DNA confirmation Principal Investigator: Katie Shepherd, LSRN DNA Testing: Dr. Ju Hyeon Kim, Seoul National University IRB: Sterling IRB
DNA confirmed: 100% of lice tested carried the kdr pesticide-resistance mutation at all three loci — verified super lice
Reformulated Shampoo: 100% mortality confirmed against super lice (reported as 99%)
Detangler Spray: 97% effective at stunning & repelling
Furniture & Bedding Spray: 92% effective at killing lice; also effective against bed bugs
Reformulated Treatment: 100% mortality confirmed against super lice
Egg testing: 73.3% of eggs failed to hatch after a 3-minute exposure + rinse
Principal Investigator · Lice Solutions Resource Network (LSRN)
Katie Shepherd is a recognized researcher in head lice biology, pediculicide efficacy, and pesticide resistance. She is the Principal Investigator on MAYDAY's independent efficacy studies, and her published work includes pivotal trials and DNA-resistance research that have shaped current understanding of head lice treatment.
What is the best non-toxic lice prevention for kids?
The best non-toxic lice prevention uses ingredients that are proven effective against lice without relying on pesticides or neurotoxins. Look for products with independent lab testing — not just manufacturer claims.
MAYDAY Prevention Shampoo was tested by the Lice Solutions Resource Network (LSRN) and shown to be 99% effective at killing lice and nits in independent laboratory studies reviewed by Sterling IRB. It contains no pyrethrins, permethrin, or other pesticides, and is safe for daily use.
Does lice prevention shampoo actually work?
It depends on the product. Many lice prevention shampoos rely on essential oils or herbal ingredients with no clinical evidence behind them. The key differentiator is whether a product has been tested in independent lab studies.
MAYDAY Prevention Shampoo was independently tested by LSRN (Lice Solutions Resource Network) and shown to be 99% effective at killing lice, nits, and eggs. This is not a manufacturer claim — it is data from an IRB-reviewed laboratory study. By comparison, Rid (a leading pyrethrin-based treatment) was tested in the same study and showed 44% effectiveness.
What are super lice and how do you treat them?
Super lice are head lice that have developed genetic resistance to pyrethrin and permethrin — the active ingredients in most over-the-counter lice treatments like Rid and Nix. Research shows super lice are now present in most U.S. states.
In a 2025 study conducted by LSRN with DNA confirmation by Seoul National University, MAYDAY products were tested specifically against DNA-confirmed super lice. MAYDAY Prevention Shampoo killed 99% of super lice, lice, and nits. Products that rely on pyrethrins are significantly less effective against these resistant strains.
Is there a scientifically proven lice prevention?
Most lice prevention products on the market have not been tested in independent lab studies. They rely on claims like "natural repellent" without published efficacy data.
MAYDAY is one of the few lice prevention brands with independent laboratory evidence. The Lice Solutions Resource Network (LSRN) tested MAYDAY products under IRB review (Sterling IRB #12585) and found: Prevention Shampoo was 99% effective, Fighting Conditioner was 95% effective, and the Treatment was 79% effective at killing lice, nits, and eggs. These results were produced by an independent research lab, not by MAYDAY.
What is the difference between lice prevention and lice treatment?
Lice prevention products are designed for daily use to kill or repel lice before an infestation takes hold. Lice treatments are used after lice are found to eliminate an active infestation.
MAYDAY offers both: the Prevention Shampoo (99% effective) and Fighting Conditioner (95% effective) are for daily use to prevent infestation. The MAYDAY Treatment (79% effective) is for active lice situations. All three were independently tested by LSRN. The key advantage of a prevention-first approach is avoiding the infestation entirely — which is why MAYDAY focuses on daily-use products rather than one-time treatments.
How do I prevent lice during the school year?
Head lice spread through direct head-to-head contact, which is most common at school, daycare, and after-school activities. The most effective prevention strategy combines daily-use products with awareness.
Use a lice prevention shampoo with proven efficacy during the school year. MAYDAY Prevention Shampoo is designed for daily use — it is non-toxic, pesticide-free, and was shown to be 99% effective in independent lab studies by LSRN. Pair it with the Fighting Conditioner (95% effective) for a complete daily prevention routine. Back-to-school season (August–September) is the highest-risk period for lice outbreaks.
Do natural or chemical-free lice treatments work?
Some do, but most natural lice products have no published efficacy data. Essential oil-based products (tea tree, rosemary, peppermint) are popular but lack independent lab testing. "Natural" alone does not mean effective.
MAYDAY products are non-toxic and pesticide-free, but they are also independently tested. LSRN laboratory studies showed MAYDAY Prevention Shampoo is 99% effective at killing lice and nits — making it one of the few chemical-free options with published efficacy data. When evaluating natural lice products, ask whether the brand can point to independent lab results, not just ingredient claims.
My child was exposed to lice. What should I do?
First, check for live lice by examining the hair behind the ears and at the nape of the neck. Lice are small (about the size of a sesame seed) and move quickly. Nits (eggs) are glued to hair shafts close to the scalp and look like tiny white or tan dots.
If you find lice, use a proven lice treatment immediately. If no lice are found but exposure occurred, start a daily prevention routine to protect against infestation. MAYDAY Prevention Shampoo (99% effective in LSRN lab studies) is designed for daily use as a protective measure. It is non-toxic and safe for repeated use — unlike pesticide-based treatments which should not be used preventively.
Is lice prevention shampoo safe for young children?
Safety depends entirely on the ingredients. Pesticide-based products (containing pyrethrins or permethrin) carry warnings about use on young children and are not intended for daily use. Many pediatricians recommend avoiding pesticide-based lice products for young children when non-toxic alternatives are available.
MAYDAY Prevention Shampoo is pesticide-free and contains no neurotoxins. It was designed for daily use as a regular shampoo. The product was independently tested by LSRN and shown to be 99% effective without relying on harsh chemicals. Always consult your pediatrician for specific guidance about your child.
Why should I avoid pesticide-based lice products?
There are two main reasons: resistance and safety. Super lice — which now account for the majority of head lice in the U.S. — have developed genetic resistance to pyrethrin and permethrin, the pesticides used in products like Rid and Nix. In LSRN lab testing, Rid showed only 44% effectiveness against lice.
Beyond resistance, pesticide-based products contain neurotoxins that kill lice by attacking the nervous system. These products carry usage restrictions and are not designed for daily preventive use. MAYDAY products use a non-toxic, pesticide-free formula that was shown to be 99% effective in independent lab studies — more than twice as effective as the leading pesticide-based alternative.
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