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Malathion

Medically reviewed by Drugs.com. Last updated on Jul 10, 2020.

Pronunciation

(mal a THYE on)

Dosage Forms

Excipient information presented when available (limited, particularly for generics); consult specific product labeling.

Lotion, External:

Ovide: 0.5% (59 mL) [contains isopropyl alcohol]

Generic: 0.5% (59 mL)

Brand Names: U.S.

  • Ovide

Pharmacologic Category

  • Antiparasitic Agent, Topical
  • Pediculocide
  • Scabicidal Agent

Pharmacology

Organophosphate that acts as a pediculicide by inhibiting cholinesterase activity in Pediculus humanus capitis (head lice and their ova)

Use: Labeled Indications

Head lice infection: Topical treatment of Pediculus humanus capitis (head lice and their ova) of the scalp hair

Off Label Uses

Pubic lice (Pediculosis pubis)

Based on the Centers for Disease Control and Prevention (CDC) sexually transmitted diseases treatment guidelines, malathion is an effective and recommended alternative agent in the treatment of pediculosis pubis (ie, pubic lice) when treatment failure has occurred with pediculicides (permethrin and pyrethrins).

Contraindications

Hypersensitivity to malathion or any component of the formulation; use in neonates and/or infants

Dosing: Adult

Head lice (Pediculus humanus capitis): Topical: Apply sufficient amount to cover and thoroughly moisten dry hair and scalp; allow hair to dry naturally and shampoo after 8 to 12 hours. If required, repeat with second application in 7 to 9 days. Further treatment is generally not necessary.

Pubic lice (Pediculosis pubis) (following treatment failure of pediculicides) (off-label use): Adults: Topical: Apply to affected area. Wash off after 8 to12 hours (CDC [Workowski 2015]).

Dosing: Geriatric

Refer to adult dosing.

Dosing: Pediatric

Head lice:

Children 2 to 5 years: Limited data available: Note: Only use for head lice resistant to permethrin/pyrethrins or previously failed courses: Topical: Apply sufficient amount to cover and thoroughly moisten dry hair and scalp, leave on for 8 to 12 hours (typically overnight application); may shampoo upon completion; during clinical trials, a maximum dose of ~60 mL (2 fl oz) was used (AAP [Devore 2015]). Note: In a blinded, comparative trial with permethrin in older children, a shorter application time of 20 minutes was shown effective (AAP [Devore 2015]; Meinking 2004). Further treatment is generally not necessary.

Children ≥6 years and Adolescents: Topical: Apply sufficient amount to cover and thoroughly moisten dry hair and scalp, leave on for 8 to 12 hours (typically overnight application); may shampoo upon completion; if live lice are observed 7 to 9 days after application, reapply product; during clinical trials, a maximum dose of ~60 mL (2 fl oz) was used. Note: In a blinded, comparative trial with permethrin, a shorter application time of 20 minutes was shown effective (AAP [Devore 2015]; Meinking 2004). Further treatment is generally not necessary.

Pubic lice (Pediculosis pubis) resistant to permethrin/pyrethrins or previously failed courses: Limited data available: Adolescents: Topical: Apply to affected area. Wash off after 8 to12 hours (CDC [Workowski 2015])

Administration

Topical lotion. For external use only; avoid contact with eyes. Apply to dry hair and scalp and rub gently until thoroughly moistened; pay special attention to the back of the head and neck. Allow hair to dry naturally; do not use heat; leave hair uncovered. After 8-12 hours, the hair should be washed with a nonmedicated shampoo; rinse and use a fine-toothed (nit) comb to remove dead lice and eggs. Evaluate other family members to determine if infested and require treatment. Wash hands immediately after use.

Malathion should be a portion of a whole household lice removal program, which should include washing or dry cleaning all clothing, hats, bedding, and towels recently worn or used by the patient and washing combs, brushes, and hair accessories in hot soapy water.

Storage

Store at room temperature 20°C to 25°C (68°F to 77°F). Do not expose to heat and open flames.

Drug Interactions

There are no known significant interactions.

Adverse Reactions

Frequency not defined.

Dermatologic: Skin irritation (including scalp irritation), stinging of the skin

Ophthalmic: Conjunctivitis (following contact with eyes)

Miscellaneous: Burn (chemical; including second-degree burns)

Warnings/Precautions

Concerns related to adverse effects:

• Dermatologic effects: Discontinue use temporarily if skin irritation occurs. Chemical burns, including second-degree burns, and stinging sensations may occur with use.

Other warnings/precautions:

• Appropriate use: For topical use on scalp hair only; leave hair uncovered after application (allow hair to dry naturally). Avoid contact with eyes; flush immediately with water if eye contact occurs. Wash hands immediately after application.

• Flammable: Lotion is flammable; do not expose lotion or hair wetted with malathion to open flames or electric heat sources (eg, hair dryer, curling iron, flat iron). Do not smoke while applying lotion or while hair is wet.

Pregnancy Risk Factor

B

Pregnancy Considerations

Adverse events have not been observed in animal reproduction studies

Patient Education

What is this drug used for?

• It is used to treat head lice.

WARNING/CAUTION: Even though it may be rare, some people may have very bad and sometimes deadly side effects when taking a drug. Tell your doctor or get medical help right away if you have any of the following signs or symptoms that may be related to a very bad side effect:

• Burning

• Stinging

• Application site irritation

• Signs of an allergic reaction, like rash; hives; itching; red, swollen, blistered, or peeling skin with or without fever; wheezing; tightness in the chest or throat; trouble breathing, swallowing, or talking; unusual hoarseness; or swelling of the mouth, face, lips, tongue, or throat.

Note: This is not a comprehensive list of all side effects. Talk to your doctor if you have questions.

Consumer Information Use and Disclaimer: This information should not be used to decide whether or not to take this medicine or any other medicine. Only the healthcare provider has the knowledge and training to decide which medicines are right for a specific patient. This information does not endorse any medicine as safe, effective, or approved for treating any patient or health condition. This is only a limited summary of general information about the medicine's uses from the patient education leaflet and is not intended to be comprehensive. This limited summary does NOT include all information available about the possible uses, directions, warnings, precautions, interactions, adverse effects, or risks that may apply to this medicine. This information is not intended to provide medical advice, diagnosis or treatment and does not replace information you receive from the healthcare provider. For a more detailed summary of information about the risks and benefits of using this medicine, please speak with your healthcare provider and review the entire patient education leaflet.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.