Review links higher primaquine doses with fewer malaria recurrences
An analysis of patients with uncomplicated vivax malaria in Latin America found fewer recurrences with a higher total dose, while safety data for the highest daily dose remained limited.
High evidenceReviewSome caution advised
Medical disclaimer: This article summarizes research findings and is for informational purposes only. It is not medical advice.
Editorial illustration — not from the study.
The review examined studies published from 2000 through July 3, 2026. It compared recurrence rates after different total primaquine doses and also assessed gastrointestinal symptoms and haemolysis, a potentially serious breakdown of red blood cells, after treatment.
Within 150 days of completing treatment, recurrence occurred in 8.7% of patients given at least 5 mg/kg in total, compared with 30.8% of those given 2 to less than 5 mg/kg. The analysis estimated that the higher-total-dose group had a lower recurrence rate, but this association does not by itself establish that dose alone caused the difference. No acute haemoglobin drop meeting the study's specified threshold was observed among 501 patients with at least 30% G6PD activity, although only seven patients received the highest daily dose.
What the review examined
Researchers conducted a systematic review and individual patient data meta-analysis. They searched five medical databases for prospective clinical efficacy studies of people with uncomplicated Plasmodium vivax malaria in Latin America who received daily primaquine within 28 days of treatment aimed at clearing the blood-stage infection. Of 40 eligible studies, data from 13 studies involving 1,734 patients were available for the main analyses. The researchers assessed any vivax recurrence within 150 days after the last primaquine dose, gastrointestinal symptoms 5–7 days after starting primaquine, and haemolysis during days 1–14. The review was registered in PROSPERO.
What the evidence shows
The estimated cumulative incidence of recurrence within 150 days was 68.2% among 119 patients who did not receive primaquine, 30.8% among 1,000 patients receiving a low total dose of 2 to less than 5 mg/kg, and 8.7% among 286 patients receiving at least 5 mg/kg in total. Compared with the low-total-dose group, the high-total-dose group had a lower estimated rate of recurrence, with an adjusted hazard ratio of 0.36 and a 95% confidence interval of 0.21 to 0.62.
Gastrointestinal symptoms were reported in 1.1% of patients receiving less than 0.375 mg/kg per day and 2.6% receiving 0.375 to less than 0.75 mg/kg per day. None of 501 patients with at least 30% G6PD activity had an acute haemoglobin decrease of more than 25% to below 7 g/dL within 14 days. However, only seven patients received at least 0.75 mg/kg per day, so the highest daily dose had limited safety data. These results are associations from a pooled analysis of clinical studies and should not be read as proof that one dose is appropriate for every patient.
Who this is relevant to
The findings are most directly relevant to people with uncomplicated Plasmodium vivax malaria treated in Latin American settings similar to those represented in the included studies, particularly those with G6PD activity of at least 30% for the reported haemolysis findings. They may not apply to people with lower G6PD activity, other forms or severities of malaria, children or other groups insufficiently represented in the studies, different regions, or treatment schedules not examined here. The results are research evidence and do not by themselves determine what treatment is appropriate for an individual.
Why it matters
Vivax malaria can recur after the initial illness, so understanding how primaquine dosing relates to recurrence and adverse effects is clinically relevant. This analysis provides information from human studies in Latin America and found a substantially lower observed recurrence rate with a higher total dose. It does not establish a universal dosing regimen, and the findings do not necessarily apply outside similar patient groups, regions, treatment settings, or G6PD activity levels.
Limitations & evidence assessment
Only 13 of the 40 eligible studies contributed individual patient data, and the abstract does not fully describe how the studies differed or how treatment groups were assigned. Because this was a pooled analysis of clinical studies rather than one clearly identified randomized comparison, differences between patients or study settings could have influenced the recurrence results. Follow-up for the main outcome was limited to 150 days after the last dose. Safety information for the highest daily dose was especially limited because only seven patients received it, and the haemolysis analysis included patients with at least 30% G6PD activity, so it does not address people with lower activity. The abstract also provides limited detail about the completeness of safety reporting and other possible sources of bias.
Why this evidence level: Meta-analysis pooling multiple studies sits at the top of common evidence hierarchies.
Evidence levels are editorial estimates derived from study metadata — they are not clinical appraisals.
// Source
The Lancet Regional Health - Americas · 2026 · DOI: 10.1016/j.lana.2026.101634
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