Mental health: Managing side effects

Last updated: Thursday, June 16, 2016

You may be asked for advice on how to manage side effects in patients taking psychiatric medicines. These clinical problems don’t differ a great deal from other adverse effect questions. However, because of their pharmacology, psychiatric drugs can be associated with syndromes or groups of adverse effects rather than individual complaints. Here are some examples:


Example signs and symptoms
Example agents implicated
Serotonin syndrome
Altered mental status (e.g. agitation, confusion).
Most antidepressants, St John’s Wort, tramadol, triptans, pethidine, lithium.
Neuromuscular hyperactivity (e.g. tremor, clonus).
Autonomic hyperactivity (e.g. sweating, fever, tachycardia).
Syndrome of inappropriate antidiuretic hormone secretion (SIADH)
Initially hyponatraemia, weakness, lethargy, weight gain without oedema, muscle cramps, vomiting and anorexia. 
In acute/severe cases confusion, coma, convulsions, death.
Antidepressants (all classes), antipsychotics, benzodiazepines, carbamazepine and oxcarbazepine.
Anticholinergic (antimuscarinic) excess

CNS (e.g. sedation, restlessness, irritability, confusion).
Antidepressants (TCAs, paroxetine), antipsychotics (olanzapine, clozapine, typical agents), anticholinergics (e.g. hyoscine, procyclidine).
Ocular (e.g. dry eyes, dilated pupils, blurred vision).
Cardiovascular (e.g. tachycardia, flushing).
Gastrointestinal (e.g. dry mouth, constipation).
Genitourinary (e.g. urinary retention).
Sweat glands (e.g. decreased sweating, increased temperature which can lead to death).
Extrapyramidal syndromes
Acute dystonia (involuntary muscle contraction)
Antipsychotics, antidepressants, lithium.
Akathisia (increased restlessness often in lower limbs, feeling of ‘unease’ and irritability)
Parkinsonism (bradykinesia, tremor, rigidity)
Tardive dyskinesia (involuntary movement including myoclonic jerks, tics, chorea and dystonia).