What is the recommended dose of hydroxychloroquine (HCQ) for malaria prophylaxis?

Hydroxychloroquine for Malaria Prophylaxis Dosing

For malaria prophylaxis, hydroxychloroquine is dosed at 400 mg (base) once weekly, starting 2 weeks before travel to endemic areas, continuing weekly during travel, and for 4 weeks after leaving the malarious region. 1

Standard Prophylaxis Regimen

Adult Dosing

• 400 mg once weekly (equivalent to 310 mg base) 1
• Begin 2 weeks prior to departure to endemic area 1
• Continue same weekly dose throughout stay in malarious region 1
• Maintain for 4 weeks after leaving endemic area 1

Pediatric Dosing (≥31 kg)

• 6.5 mg/kg actual body weight (up to 400 mg) once weekly 1
• Same timing schedule as adults 1
• Not recommended for children <31 kg because the 200 mg tablet cannot be divided and exceeds safe dosing 1

Administration Guidelines

• Take with food or milk to minimize gastrointestinal side effects 1
• Do not crush or divide tablets 1
• Administer on the same day each week for consistency 1

Clinical Context and Limitations

When Hydroxychloroquine is Appropriate

Hydroxychloroquine is interchangeable with chloroquine for malaria prophylaxis in areas without chloroquine resistance 2. Both drugs rarely cause serious adverse reactions at prophylactic doses, with minor side effects including gastrointestinal disturbance, headache, dizziness, blurred vision, and pruritus 2.

Critical Limitation: Chloroquine-Resistant Areas

Hydroxychloroquine is significantly less effective against chloroquine-resistant P. falciparum - it is 8.8 times less active than chloroquine against resistant strains 3. In chloroquine-resistant areas, first-line alternatives include:

• Mefloquine (250 mg weekly for adults) in areas with high chloroquine resistance 4
• Doxycycline as alternative for short-term travelers or in mefloquine-resistant areas 2, 4
• Atovaquone-proguanil for areas with chloroquine resistance 4

Important Safety Considerations

• Periodic ophthalmologic examinations recommended for persons using hydroxychloroquine for extended periods (>6 years cumulative weekly prophylaxis) 2
• May exacerbate psoriasis 2
• May interfere with antibody response to intradermal human diploid cell rabies vaccine 2
• Daily doses exceeding 5 mg/kg actual weight increase retinopathy risk 1

Common Pitfalls to Avoid

Compliance Issues

Most malaria deaths occur in travelers who do not fully comply with prophylaxis regimens 4. Emphasize to patients:

• The importance of starting 2 weeks before travel (allows time to assess tolerance and achieve protective levels) 4
• Continuing for full 4 weeks after leaving endemic area (covers incubation period) 1
• Taking medication on same day each week 1

Inadequate Protection Against Relapsing Malaria

Hydroxychloroquine does not prevent relapses from P. vivax or P. ovale liver stages (hypnozoites), which can remain dormant for up to 4 years 4, 5. For travelers with prolonged exposure to these species, primaquine prophylaxis should be added during the last 2 weeks of the 4-week post-exposure period after G6PD testing 2.

No Prophylaxis is 100% Effective

No prophylactic regimen guarantees complete protection 4. Advise patients to:

• Use insect repellents containing DEET on exposed skin 4
• Wear long-sleeved clothing and long trousers after sunset 4
• Use pyrethrum-containing flying-insect spray in living/sleeping areas 4
• Seek immediate medical evaluation if fever develops during or after travel 4