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GABA-B Receptor Agonist (Muscle Relaxant / Antispastic) Pregnancy: During pregnancy, especially first three months, use only if of vital necessity; weigh maternal benefit against fetal risk. Baclofen crosses the placenta (neonatal withdrawal convulsions reported). Passes into breast milk in quantities too small to expect undesirable effects at therapeutic maternal doses.

Baclofen

Brand names: Lioresal

Baclofen is a muscle relaxant used for chronic severe spasticity, for example in multiple sclerosis or spinal cord conditions.

Auto-extracted from the source labelling — not yet independently clinician-verified. These values were distilled from the UK SPC (or the US label where noted) but have not had a clinician sign-off. Confirm against the current SmPC before prescribing.

Adult dose

Dose: 5 mg three times a day, titrated gradually (usual control up to 60 mg daily)
Route: Oral
Frequency: Three times a day
Max: Maximum >100 mg not advised unless patient is in hospital under careful medical supervision
Gradually increasing regimen suggested, adjusted to individual requirements: 5 mg three times a day for 3 days, then 10 mg three times a day for 3 days, then 15 mg three times a day for 3 days, then 20 mg three times a day for 3 days. Satisfactory symptom control usually obtained with doses up to 60 mg daily. Small frequent dosing may be better than larger spaced doses. Some patients benefit from baclofen only at night for painful flexor spasm, or a single dose ~1 hour before specific tasks. If therapeutic effect not apparent within six weeks of reaching maximum recommended dose, decide whether to continue. Elderly: use small starting doses, titrate gradually under supervision. Patients with spastic states of cerebral origin: adopt a very cautious dosage schedule.

Paediatric dose

Route: Oral
Frequency: 2–4 divided doses (preferably 4)
Max: 40 mg/day in children below 8 years; 60 mg/day in children over 8 years
Paediatric population (0–18 years): start at a very low dose ~0.3 mg/kg/day in 2–4 divided doses (preferably 4). Raise cautiously at about 1-week intervals until sufficient for the child's requirements. Usual maintenance daily dose 0.75–2 mg/kg body weight. Baclofen tablets are NOT suitable for children below 33 kg body weight.

Dose adjustments

Renal

Impaired renal function or chronic haemodialysis: select a particularly low dosage, approx. 5 mg daily. Signs of overdose observed with more than 5 mg oral baclofen/day in renal impairment. Administer to end-stage renal failure (CKD stage 5, GFR <15 mL/min) only if expected benefit outweighs risk, with close monitoring.

Dose auto-extracted from UK Summary of Product Characteristics (SPC) via the eMC; US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — not yet clinician-verified. Always confirm against the product SmPC and your local formulary before prescribing.

US labelling (FDA)

Reference — US labelling, may differ from UK

DOSAGE AND ADMINISTRATION The determination of optimal dosage requires individual titration. Start therapy at a low dosage and increase gradually until optimum effect is achieved (usually between 40-80 mg daily). The following dosage titration schedule is suggested: 5 mg t.i.d. for 3 days 10 mg t.i.d. for 3 days 15 mg t.i.d. for 3 days 20 mg t.i.d. for 3 days Thereafter additional increases may be necessary but the total daily dose should not exceed a maximum of 80 mg daily (20 mg q.i.d.). The lowest dose compatible with an optimal response is recommended. If benefits are not evident after a reasonable trial period, patients should be slowly withdrawn from the drug (See WARNINGS , Abrupt …

Source: US FDA prescribing information (openFDA / DailyMed), label dated 2026-01-21. Accessed 2026-06-12. US dosing and indications can differ from UK practice — use UK sources for prescribing decisions.

Contraindications

  • Hypersensitivity to baclofen or to any excipient
  • Peptic ulceration

Side effects

  • Somnolence, sedation (very common)
  • Nausea (very common)
  • Respiratory depression, confusional state, dizziness, muscular weakness, fatigue (common)
  • Hypotension (common)
  • Constipation, diarrhoea, vomiting (common)

Interactions

  • Antihypertensive therapy — use with extreme care (additive hypotension)

Clinical monograph

How it works

It is a GABA-B receptor agonist that reduces spinal reflex transmission and so muscle tone.

Prescribing in practice

  • Do not stop it abruptly after regular use — withdrawal can cause rebound spasticity, hallucinations and seizures; taper instead.
  • Sedation, drowsiness and muscle weakness are common; start low and titrate.
  • Reduce the dose in renal impairment; intrathecal baclofen overdose or withdrawal is a medical emergency.

Monitoring

Review spasticity benefit, sedation and function; check renal function where relevant.

Counselling the patient

  • Do not stop it suddenly.
  • It can cause drowsiness — take care driving until you know how it affects you.
  • Tell your clinician if it makes you too weak.

Evidence & guidelines

Used for chronic severe spasticity (e.g. multiple sclerosis, spinal injury), titrated to balance tone reduction against weakness and sedation.

Reference: NICE CG186 (Spasticity); MHRA SPC Lioresal; ALPADIR trial (Reynaud et al. 2017 — alcohol dependence off-label); Cochrane Review — antispastics in MS; 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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