| Pharmacologic agent | Efficacy and comment | Side effects |
| Dopamine agonists | Dramatic response in the dopa-responsive form of dystonia; effective in 10 to 15% of patients with other types of dystonia; more rapid upward titration possible | Nausea (especially at initiation of therapy); may worsen dystonia; rapid discontinuation possible |
Anticholinergic/antihistaminic - Trihexyphenidyl
- Benztropine
- Procyclidine
- Diphenhydramine
- Ethopropazine
| Effective in approximately 40% of patients, mainly children; benefit limited by side effects; requires slow upward titration | Dry mouth (may lead to dental caries); blurred vision; exacerbation of acute-angle glaucoma; urinary retention; memory problems; sedation; confusion; hallucinations; heat intolerance |
| Baclofen | Effective in approximately 20% of patients; high doses tolerated in children; benefits limited by side effects; intrathecal baclofen minimally successful; withdrawal effects on sudden discontinuation | Nausea; sedation; dysphoria; muscle weakness (in those with spasticity associated) |
| Benzodiazepines | Effective in approximately 15% of patients; possibility for addiction; withdrawal effects on sudden discontinuation | Sedation; depression; confusion; dependence |
Muscle relaxants - Tizanidine
- Cyclobenzaprine
| Limited benefit in some patients; side effects frequent | Sedation; dysphoria |
| Antiseizure medications | Benefit in less than 10% of patients | Ataxia; sedation |
| Dopamine-depleting agents | Requires a very slow upward titration (4 weeks between dose increases) | Depression; dysphoria; parkinsonism |
| Dopamine receptor blocking agents | Effective in up to 25% of patients; clozapine requires weekly blood counts and may cause life-threatening agranulocytosis | The possibility of tardive dyskinesia and the other adverse effects from this class of medications severely limits usefulness; not recommended for dystonia |
