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Artemisinin-Based Combination Antimalarial (ACT) Pregnancy: UK SPC §4.6: a meta-analysis of observational studies including over 500 artemether-lumefantrine exposed women in the first trimester showed that, compared with quinine, artemisinin treatment 'was not associated with an increased risk of miscarriage, stillbirth or congenital anomalies', though the risk cannot be excluded given the studies' limitations; safety data from over 1,200 women exposed in the second or third trimester 'did not show an increase in adverse pregnancy outcomes or teratogenic effects over background rates'. Animal studies have shown reproductive toxicity. 'Riamet treatment is not recommended during the first trimester of pregnancy in situations where other suitable and effective antimalarials are available. However, it should not be withheld in life-threatening situations, where no other effective antimalarials are available. During the second and third trimester, Riamet treatment should be considered if the expected benefit to the mother outweighs the risk to the foetus.' Breast-feeding: 'Women taking Riamet should not breast-feed during their treatment... it is recommended that breast-feeding should not resume until at least one week after the last dose of Riamet unless potential benefits to the mother and child outweigh the risks.' Women using oral, transdermal patch or other systemic hormonal contraceptives should use an additional non-hormonal method of birth control for about one month.

Artemether with Lumefantrine

Brand names: Riamet, Coartem

Artemether with lumefantrine is a fixed-dose artemisinin-based combination therapy used to treat acute uncomplicated Plasmodium falciparum malaria.

Adult dose

Dose: Treatment of acute uncomplicated Plasmodium falciparum malaria, in patients 12 years of age and above and 35 kg body weight and above: four tablets per dose (Riamet 20 mg/120 mg tablets). A course of treatment comprises six doses of four tablets, i.e. a total of 24 tablets, given over a period of 60 hours.
Route: Oral. SPC 4.2 verbatim: 'Tablets for oral administration. To increase absorption, Riamet should be taken with food or a milky drink (see section 5.2). If patients are unable to tolerate food, Riamet should be administered with water, but the systemic exposure may be reduced. Patients who vomit within 1 hour of taking the medication should repeat the dose. For administration to small children and infants, the tablet/s may be crushed.'
Frequency: Six doses over 60 hours: the first dose of four tablets given at the time of initial diagnosis, followed by five further doses of four tablets given at 8, 24, 36, 48 and 60 hours thereafter.
Section 4.1 verbatim: 'Riamet is indicated for the treatment of acute uncomplicated Plasmodium falciparum malaria in adults, children and infants of 5 kg and above.' SCOPE OF THE DOSE ABOVE: it is the 4.2 band headed 'Adults and children weighing 35 kg and above', which the SPC itself defines as 'For patients 12 years of age and above and 35 kg body weight and above'. Patients from 5 kg to less than 35 kg take the weight-banded tablet counts recorded in paedDose - the four-tablet dose must not be used for them. NO MAXIMUM DOSE IS PRINTED: the word 'maximum' does not appear anywhere in the fetched 4.1-4.8, so maxDose is deliberately absent rather than derived. The '24 tablets' figure is the SPC's stated TOTAL for the complete six-dose course, not a ceiling, and is kept inside the dose text where it cannot be read as a per-dose or per-day cap. COURSE LIMIT (4.4): new infections in an endemic area can be treated with a second course, but 'In the absence of carcinogenicity study data, and due to lack of clinical experience, more than two courses of Riamet cannot be recommended.' TABLET STRENGTH: '20 mg/120 mg' is quoted from the SPC's own product name, 'Riamet 20 mg/120 mg Tablets'. Section 2 (composition) was not fetched, so the two numbers are deliberately NOT attributed to artemether and lumefantrine individually here, and no per-dose milligram total has been calculated - the SPC expresses every dose in whole tablets and no milligram figure per dose appears anywhere in the fetched text. NOT FOR SEVERE MALARIA OR FOR PROPHYLAXIS: severe malaria by the WHO definition is a 4.3 contraindication, and 4.4 states 'Riamet is not indicated and has not been evaluated for prophylaxis of malaria.' OLDER PEOPLE (4.2): 'There is no information suggesting that the dosage in patients over 65 years of age should be different than in younger adults.' RENAL AND HEPATIC IMPAIRMENT (4.4): no dose adjustment is recommended in renal impairment, nor in mild to moderate hepatic impairment; caution is advised in severe renal impairment and in severe hepatic impairment, and in both 'ECG and blood potassium monitoring is advised'. CO-ADMINISTRATION CAUTIONS (4.4): 'Riamet should not be given concurrently with any other antimalarial agent (see section 4.5) unless there is no other treatment option'; in patients previously treated with halofantrine, Riamet should not be administered earlier than one month after the last halofantrine dose; if quinine is given after Riamet, close monitoring of the ECG is advised; if Riamet is given after mefloquine, close monitoring of food intake is advised; Riamet may reduce the effectiveness of hormonal contraceptives, so patients using oral, transdermal patch or other systemic hormonal contraceptives should use an additional non-hormonal method of birth control for about one month. That renderer has since been fixed - src/pages/drugs/[specialty]/[id].astro now prints paedDose.dose whenever dosePerKg is null - so the bands below are visible to the reader. dosePerKg remains null so that no weight-multiplying calculator can act on them. TRUNCATION: sections 4.1, 4.2, 4.3, 4.4 and 4.6-4.8 are complete in this bundle; 4.5 is cut off at the source-fetch limit inside the 'Interaction with other antimalarial drugs' paragraph, so the interaction picture below is not complete.

Paediatric dose

Dose: Weight-banded whole tablets, NOT a per-kilogram dose - 5 kg to less than 15 kg: one tablet per dose. 15 kg to less than 25 kg: two tablets per dose. 25 kg to less than 35 kg: three tablets per dose. Each band is given as the same six-dose course.
Route: Oral, with food or a milky drink to increase absorption; for administration to small children and infants the tablet/s may be crushed. A patient who vomits within 1 hour of taking the medication should repeat that dose.
Frequency: Six doses over 60 hours: the first dose at the time of initial diagnosis, then five further doses of the same number of tablets at 8, 24, 36, 48 and 60 hours thereafter.
Section 4.1 licenses Riamet in 'adults, children and infants of 5 kg and above'. BELOW 5 kg, 4.2 verbatim: 'The safety and efficacy of Riamet tablets have not been established in infants weighing less than 5 kg and no dosing recommendations can be made.' These are whole-tablet counts for a weight BAND and must never be entered into a weight-multiplying calculator - dosePerKg is null for exactly that reason, and no mg/kg figure exists anywhere in this SPC. A patient who is both 12 years of age and above and 35 kg body weight and above takes the four-tablet adult dose. The SPC's two headings ('Adults and children weighing 35 kg and above' and 'Children and infants weighing 5 kg to less than 35 kg') are reproduced as they stand; no rule has been invented for a child under 12 years who weighs 35 kg or more, because the label does not state one. No maximum is printed for any band.

Dose independently re-sourced from UK Summary of Product Characteristics (SPC) via the eMC — clinician-reviewed. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

  • Known hypersensitivity to the active substances or to any of the excipients listed in section 6.1
  • Patients with severe malaria according to WHO definition — the SPC defines this as one or more of: prostration; impaired consciousness or unarousable coma; failure to feed; deep breathing, respiratory distress (acidotic breathing); multiple convulsions; circulatory collapse or shock; pulmonary oedema (radiological); abnormal bleeding; clinical jaundice; haemoglobinuria; or the laboratory features severe normocytic anaemia, hypoglycaemia, metabolic acidosis, renal impairment, hyperlactataemia, hyperparasitaemia
  • Patients taking any drug which is metabolised by the cytochrome enzyme CYP2D6 (e.g. metoprolol, imipramine, amitriptyline, clomipramine)
  • Patients with a family history of sudden death or of congenital prolongation of the QTc interval on electrocardiograms, or with any other clinical condition known to prolong the QTc interval
  • Patients taking drugs known to prolong the QTc interval (proarrhythmic): antiarrhythmics of classes IA and III; neuroleptics and antidepressive agents; certain antibiotics including some macrolides, fluoroquinolones, imidazole and triazole antifungal agents; certain non-sedating antihistamines (terfenadine, astemizole); cisapride; flecainide
  • Patients with a history of symptomatic cardiac arrhythmias, clinically relevant bradycardia, or congestive cardiac failure accompanied by reduced left ventricular ejection fraction
  • Patients with disturbances of electrolyte balance, e.g. hypokalaemia or hypomagnesaemia
  • Patients taking drugs that are strong inducers of CYP3A4 such as rifampicin, carbamazepine, phenytoin or St John's wort (Hypericum perforatum)

Side effects

  • §4.8 gives frequencies in two columns — adults and adolescents above 12 years of age, then infants and children of 12 years of age and below (with incidence estimates). Both are given below as 'adults / children'
  • Decreased appetite — very common / very common (16.8%); headache — very common / very common (17.1%); dizziness — very common / common (5.5%); sleep disorders — very common / common (6.4%); insomnia — common / uncommon
  • Palpitations — very common / common (1.8%); electrocardiogram QT prolonged — common / common (5.3%)
  • Vomiting — very common / very common (20.2%); abdominal pain — very common / very common (12.1%); nausea — very common / common (6.5%); diarrhoea — common / common (8.4%)
  • Arthralgia — very common / common (2.1%); myalgia — very common / common (2.2%); asthenia — very common / common (5.2%); fatigue — very common / common (9.2%); gait disturbance — common / not reported
  • Cough — common / very common (22.7%); liver function tests increased — uncommon / common (4.1%)
  • Paraesthesia — common / not reported; clonus — common / uncommon; ataxia and hypoaesthesia — uncommon / not reported; somnolence — uncommon / uncommon
  • Rash — common / common (2.7%); pruritus — common / uncommon; urticaria — uncommon / uncommon; angioedema — not known / not known (post-marketing)
  • Hypersensitivity — not known / rare
  • Delayed haemolytic anaemia — not known in both groups; the SPC notes it 'has been reported up to a few weeks after treatment has been stopped'

Monitoring

  • 4.4: 'If a patient deteriorates whilst taking Riamet, alternative treatment for malaria should be started without delay. In such cases, monitoring of the ECG is recommended and steps should be taken to correct any electrolyte disturbances.'
  • 4.4: 'The long elimination half-life of lumefantrine must be taken into account when administering quinine in patients previously treated with Riamet. If quinine is given after Riamet, close monitoring of the ECG is advised.'
  • 4.4: 'If Riamet is given after mefloquine, close monitoring of food intake is advised.'
  • 4.4: 'Like other antimalarials (e.g. halofantrine, quinine and quinidine) Riamet has the potential to cause QT prolongation.'
  • 4.4: 'Patients who remain averse to food during treatment should be closely monitored as the risk of recrudescence may be greater.'
  • 4.4, severe renal impairment: no dose adjustment is recommended in renal impairment, but 'Caution is advised when administering Riamet to patients with severe renal impairment. In these patients, ECG and blood potassium monitoring is advised.'
  • 4.4, severe hepatic impairment: no dose adjustment is recommended in mild to moderate hepatic impairment, but caution should be exercised in severe hepatic impairment and 'In these patients, ECG and blood potassium monitoring is advised.'

Clinical monograph

How it works

Artemether produces reactive intermediates that rapidly kill blood-stage parasites, while lumefantrine provides slower, longer-lasting parasite clearance, reducing recrudescence.

Prescribing in practice

  • It is indicated for uncomplicated malaria only; severe or complicated malaria requires parenteral therapy such as artesunate.
  • It can prolong the QT interval, so caution is needed in patients with cardiac risk factors or other QT-prolonging drugs.
  • Absorption is improved by taking it with food or a fat-containing drink, and exposure may be altered by CYP-interacting drugs.

Monitoring

Monitor parasitaemia and clinical response, and consider ECG monitoring where there are risk factors for QT prolongation.

Counselling the patient

  • Take each dose with a fatty meal or drink to help absorption.
  • If you vomit shortly after a dose, contact your team as a repeat dose may be needed.
  • Complete the full course and report any palpitations or worsening symptoms.

Evidence & guidelines

Artemisinin-based combination therapy is the World Health Organization-recommended first-line treatment for uncomplicated falciparum malaria.

Reference: PHE/UKHSA Guidelines for Malaria Prevention and Treatment (2022); WHO Guidelines for Treatment of Malaria (3rd edition, 2015 updated); NICE CKS Malaria (2023); Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Related

Curated clinical cross-links plus same-class fallbacks.

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