Formulary
Methylthioninium chloride: Indications, Dosing, Side Effects and Interactions
Methylthioninium chloride clinical drug profile including indications, dosing, side effects, cautions and interactions.
MedNext Academy | 3 min read
Methylthioninium chloride: Indications, Dosing, Side Effects and Interactions
Methylthioninium chloride clinical drug profile including indications, dosing, side effects, cautions and interactions.
Indications and dose
**Drug- or chemical-induced methaemoglobinaemia**
- **Child** (By Slow Intravenous Injection): 3 months-17 years Initially 1-2 mg/kg, then 1-2 mg/kg after 30-60 minutes if required, to be given over 5 minutes, seek advice from National Poisons Information Service if further repeat doses are required; maximum 7 mg/kg per course.
- **Adult** (By Slow Intravenous Injection): Initially 1-2 mg/kg, then 1-2 mg/kg after 30-60 minutes if required, to be given over 5 minutes, seek advice from National Poisons Information Service if further repeat doses are required; maximum 7 mg/kg per course.
**Aniline- or dapsone-induced methaemoglobinaemia**
- **Child** (By Slow Intravenous Injection): 3 months-17 years Initially 1-2 mg/kg, then 1-2 mg/kg after 30-60 minutes if required, to be given over 5 minutes, seek advice from National Poisons Information Service if further repeat doses are required; maximum 4 mg/kg per course.
- **Adult** (By Slow Intravenous Injection): Initially 1-2 mg/kg, then 1-2 mg/kg after 30-60 minutes if required, to be given over 5 minutes, seek advice from National Poisons Information Service if further repeat doses are required; maximum 4 mg/kg per course.
**Drug- or chemical-induced methaemoglobinaemia for methylthioninium chloride**
- **Neonate** (By slow intravenous injection): Seek advice from National Poisons Information Service.
- **Child 1-2 months** (By slow intravenous injection): Seek advice from National Poisons Information Service.
- **Child 3 months-17 years** (By slow intravenous injection): Initially 1-2 mg/kg, then 1-2 mg/kg after 30-60 minutes if required, to be given over 5 minutes, seek advice from National Poisons Information Service if further repeat doses are required; maximum 7 mg/kg per course.
**Aniline- or dapsone-induced methaemoglobinaemia for methylthioninium chloride**
- **Child 3 months-17 years** (By slow intravenous injection): Initially 1-2 mg/kg, then 1-2 mg/kg after 30-60 minutes if required, to be given over 5 minutes, seek advice from National Poisons Information Service if further repeat doses are required; maximum 4 mg/kg per course.
Cautions
Children under 3 months (more susceptible to methaemoglobinaemia from high doses of methylthioninium); chlorate poisoning (reduces efficacy of methylthioninium); G6PD deficiency (seek advice from National Poisons Information Service); methaemoglobinaemia due to treatment of cyanide poisoning with sodium nitrite (seek advice from National Poisons Information Service); pulse oximetry may give false estimation of oxygen saturation
Side effects
Common or very common Abdominal pain; anxiety; chest pain; dizziness; headache; hyperhidrosis; nausea; pain in extremity; paraesthesia; skin reactions; taste altered; urine discolouration; vomiting Frequency not known Aphasia; arrhythmias; confusion; faeces discoloured; fever; haemolytic anaemia; hyperbilirubinaemia (in infants); hypertension; hypotension; injection site necrosis; mydriasis; tremor
Interactions
**Other interactions (4):**
- These include SSRIs (selective serotonin reuptake inhibitors), bupropion, buspirone, clomipramine, mirtazapine, and venlafaxine.
- Opioids, for example, tramadol, fentanyl, pethidine, and dextromethorphan, may also increase the risk of developing serotonin syndrome, when used in combination with methylthioninium chloride.
- In a drug interaction study, a single IV dose of 2 mg/kg Methylthioninium chloride Proveblue did not have a clinically relevant effect on the pharmacokinetics of midazolam (CYP3A4), caffeine...
- The administration of methylthioninium chloride Proveblue has the potential to transiently increase the exposure of drugs primarily cleared by renal transport involving the OCT2/MATE pathway,...
Pregnancy
No information available, but risk to fetus of untreated methaemoglobinaemia likely to be significantly higher than risk of treatment.
Breast feeding
Manufacturer advises avoid breastfeeding for up to 6 days after administration-no information available.
Renal impairment
National Poisons Information Service advises caution in severe impairment. Dose adjustments Manufacturer advises lower doses may be required (consult product literature).
Medicinal forms
Solution
Clinical governance
**Author:** MedNext Clinical Team. **Clinical reviewer:** Dr Shameer Deen, MBBS, MS, MRCS. **Sources:** BNF, Indian Pharmacopoeia, CIMS India. **Correction:** Report errors at support@mednext.academy.
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