Malathion is an organophosphate insecticide commonly used in agriculture, public health, and residential settings to control pests such as mosquitoes, flies, and other insects. It is also used in some pet shampoos for controlling fleas.
It works by inhibiting the action of acetylcholinesterase, an enzyme necessary for proper nerve function in insects, leading to paralysis and death. However, it can also affect non-target organisms, including humans and other animals, if not used properly.
Malathion (Ovide) is an organophosphate that when used topically over the scalp or pubic hair results in the clearance of head and pubic lice in individuals with a lice infestation.
Malathion (Ovide) Uses:
- Head lice infection:
- It is indicated for the topical treatment of head lice and their ova (Pediculus humanus capitis) of the scalp hair
- Off-Label Use of Malathion in Adults:
- It may be used for lice infesting the pubic hair (Pediculosis pubis).
Malathion (Ovide) Dose in Adults:
Malathion (Ovide) Dose in the Head lice (Pediculus humanus capitis):
- Put enough malathion on dry hair and scalp to cover them completely. Make sure the hair and scalp are fully wet.
- Let the hair air dry naturally.
- After 8 to 12 hours, wash the hair with shampoo.
- If needed, you can repeat the treatment after 7 to 9 days with another application.
- Usually, you won't need to do more treatments after this.
Malathion (Ovide) Dose in the Pubic lice (Pediculosis pubis) (following treatment failure of pediculicides) (off-label):
- For adults, apply malathion to the affected area.
- Leave it on for 8 to 12 hours.
- After that time, wash it off.
Malathion (Ovide) Dose in Children:
Malathion (Ovide) Dose in the Head lice:
For children aged 2 to 5 years:
- Malathion should only be used if head lice are resistant to permethrin/pyrethrins or if previous treatments have failed.
- Apply enough malathion to cover the dry hair and scalp completely.
- Leave it on for 8 to 12 hours, usually overnight.
- You can shampoo the hair after completion if desired.
- During clinical trials, a maximum dose of around 60 mL (2 fl oz) was used.
For children aged 6 years and older, as well as adolescents:
- Apply enough malathion to cover the dry hair and scalp completely.
- Leave it on for 8 to 12 hours, typically overnight.
- Shampoo the hair after completion if preferred.
- If live lice are still seen 7 to 9 days later, you can reapply the product.
- Similar to younger children, a maximum dose of around 60 mL (2 fl oz) was used in clinical trials.
Note: In some studies, a shorter application time of 20 minutes was also effective when compared to permethrin. Further treatment is generally not necessary unless live lice are observed after the initial treatment.
Malathion (Ovide) dose in the Pubic lice (Pediculosis pubis) resistant to permethrin/pyrethrins or previously failed courses:
For adolescents with pubic lice (Pediculosis pubis) resistant to permethrin/pyrethrins or if previous treatments have failed:
- Apply malathion to the affected area.
- Leave it on for 8 to 12 hours.
- After that time, wash it off.
Pregnancy Risk Factor B
- During pregnancy, malathion is considered a Risk Factor B, meaning adverse effects haven't been seen in animal studies related to reproduction.
Use during breastfeeding:
- It's uncertain whether the malathion 0.5% lotion gets into breast milk.
- If it's used by or applied by mothers who breastfeed, it's advisable to be cautious.
Dose in Kidney Disease:
The manufacturer's labeling does not include any specific adjustments to the dosage for individuals with renal impairment.
Dose in Liver disease:
The manufacturer's labeling does not include any specific adjustments to the dosage for individuals with hepatic impairment.
Side effects of Malathion (Ovide):
- Dermatologic:
- Skin irritation (including scalp irritation)
- Stinging of the skin
- Ophthalmic:
- Conjunctivitis (following contact with eyes)
- Miscellaneous:
- Burn (chemical; including second-degree burns)
Contraindications to Malathion (Ovide):
- Malathion should not be used if someone is hypersensitive to it or any component of the formulation.
- Additionally, it is not recommended for use in neonates and/or infants.
Warnings and precautions
Dermatologic effects
- If skin irritation occurs while using malathion, it's advised to temporarily stop its use.
- Malathion can cause chemical burns, including second-degree burns, as well as stinging sensations.
Monitoring Parameters:
Monitor for clearance of lice infestation in the whole family members.
How to administer Malathion (Ovide)?
- Topical Lotion: Malathion is a lotion meant for use on the skin.
- External Use Only: Avoid getting the lotion in the eyes.
- Application: Apply the lotion to dry hair and scalp, gently rubbing until everything is moistened. Pay extra attention to the back of the head and neck.
- Drying: Let the hair air dry naturally. Don't use heat and keep the hair uncovered.
- Washing: After 8-12 hours, wash the hair with a shampoo that doesn't contain medication.
- Removing Lice and Eggs: Use a fine-toothed comb to remove any dead lice and eggs from the hair.
- Check Family Members: See if other family members have lice and need treatment.
- Hand Washing: Wash hands immediately after using the lotion.
Comprehensive Lice Removal Program:
- Whole Household Approach: Malathion treatment should be part of a plan to get rid of lice from the entire household.
- Wash or Dry Clean Clothing: Clean all clothing, hats, bedding, and towels that the patient has recently worn or used.
- Clean Hair Accessories: Wash combs, brushes, and hair accessories in hot, soapy water.
Mechanism of action of Malathion (Ovide):
Malathion is an organophosphate that works as a treatment for head lice by stopping cholinesterase activity in Pediculus humanus capitis, which includes both the lice and their eggs.
International Brand Names of Malathion:
- Ovide
- A-Lices
- A-Lices 1%
- Aftir Gel
- Derbac-M
- Lice Care
- Lice Clean
- Lice Rid
- Malation
- Malthionex
- Olicide
- Organoderm
- Piojisar M
- Prioderm
- Quellada-M
- Radikal
Malathion Brand Names in Pakistan:
No Brands Available in Pakistan.
