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Malathion

Medically reviewed by Drugs.com. Last updated on Jul 4, 2019.

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

• Discuss specific use of drug and side effects with patient as it relates to treatment. (HCAHPS: During this hospital stay, were you given any medicine that you had not taken before? Before giving you any new medicine, how often did hospital staff tell you what the medicine was for? How often did hospital staff describe possible side effects in a way you could understand?)

• Have patient report immediately to prescriber burning, stinging, or application site irritation (HCAHPS).

• Educate patient about signs of a significant reaction (eg, wheezing; chest tightness; fever; itching; bad cough; blue skin color; seizures; or swelling of face, lips, tongue, or throat). Note: This is not a comprehensive list of all side effects. Patient should consult prescriber for additional questions.

Intended Use and Disclaimer: Should not be printed and given to patients. This information is intended to serve as a concise initial reference for health care professionals to use when discussing medications with a patient. You must ultimately rely on your own discretion, experience, and judgment in diagnosing, treating, and advising patients.

Further information

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

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