Centrally acting muscle relaxant
ATC code: M03BX05 (Thiocolchicoside)
A semisynthetic colchicoside derivative with agonist action on GABA-A and glycine receptors in the spinal cord. Reduces reflex muscle spasm by inhibiting motor neurons. The SL18.0740 metabolite showed aneugenic activity in in vitro and in vivo studies – chromosomal damage with mutagenic potential for germ cells and the fetus. Based on these findings, in 2014 restricted indications and shortened course length.
Adjunct
Add-on therapy for acute painful skeletal muscle spasm in adults over 16, alongside analgesics. Per the 2014 decision, oral courses are limited to 7 days (8 mg twice daily) and IM courses to 5 days (4 mg twice daily). Evidence versus other muscle relaxants is weak; placebo advantage is modest (Tüzün 2016 meta-analysis).
Adults over 16 only, maximum 5–7 days.
The drug is promoted for these uses outside international guidelines. Each entry below is analyzed against AEMPS, FDA, EMA, Cochrane and major RCTs.
Not recommended
Thiocolchicoside is a centrally acting muscle relaxant, an agonist at GABA-A and glycine receptors. It is prescribed in short courses for acute painful muscle spasm associated with spinal or muscular pathology (AEMPS Ficha Técnica, maximum 5-7 days). In anti-aging regimens, thiocolchicoside is used long-term for muscle relaxation in healthy adults. Long-term use is not justified: in 2014 the restricted thiocolchicoside to short courses for acute muscle spasm after evidence of genotoxicity of the active metabolite (DNA damage risk and potential carcinogenicity). The drug is not approved in the US ( has not approved it). Specific risks: diarrhea, allergic reactions, and seizures (especially with dose exceedance or in those predisposed to epilepsy). If thiocolchicoside was prescribed for chronic use in muscle tension, consider seeking a second opinion.
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Absolute contraindication throughout pregnancy. The SL18.0740 metabolite is potentially mutagenic and teratogenic. Reliable contraception is mandatory in women of reproductive age on therapy.
Thiocolchicoside and its metabolites pass into milk. Breastfeeding is contraindicated during therapy.
Reference information, not a clinical decision. Discuss feeding pauses or changes with your physician or an IBCLC.
Thiocolchicoside is evaluated for the following indications with varying evidence strength: Acute painful muscle spasm (evidence tier C), Anti-aging and longevity (evidence tier F). See the full indication matrix with dosing and citations above on this page.
Common side effects of Thiocolchicoside (≥ 1 in 100): Nausea, vomiting, Diarrhea, Abdominal pain, Drowsiness, Allergic skin reactions. See the Safety section for uncommon and serious reactions.
FDA category D. Absolute contraindication throughout pregnancy. The SL18.0740 metabolite is potentially mutagenic and teratogenic. Reliable contraception is mandatory in women of reproductive age on therapy.
Thiocolchicoside and its metabolites pass into milk. Breastfeeding is contraindicated during therapy.
Thiocolchicoside is contraindicated in: Hypersensitivity to thiocolchicoside or colchicine; Pregnancy and lactation; Women of reproductive age without reliable contraception; Age under 16; Flaccid paralysis and muscle hypotonia. Full list in the Safety section.