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Table 1 Main classes of mood stabiliser (and alternatives to valproate in the treatment of bipolar disorder), mechanisms of action and side effects (not including foetal or maternal risks). Compiled from various sources [10, 33, 34, 91,92,93,94,95,96,97,98,99,100]

From: Sodium valproate in pregnancy: what are the risks and should we use a shared decision-making approach?


Medication name

Proposed mechanism(s) of action

Side effects



Enhances serotonergic neuron activity, inhibits pAp-phosphatase enzyme, interacts with nitric oxide signalling activity

Common: GI upset, fine tremor, polyuria, polydipsia, metallic taste in mouth, ankle oedema, weight gain. Chronic: renal toxicity, hypothyroidism.


Sodium valproate

GABA potentiation, blocks voltage gated sodium channels, epigenetically inhibits histone deacetylase

Common: GI upset, hyperammonaemia (causing nausea), weight gain, tremor, hair loss with curly regrowth.

In women: polycystic ovarian syndrome, hyperandrogenism.

Rare: fulminant liver failure.


GABA potentiation, suppresses glutamate release, inhibits serotonin reuptake

Common: tremors, dizziness, tiredness, loss of co-ordination, menstrual disturbance, dry mouth, sleep problems.


Blocks voltage gated sodium channels

Common: dizziness, diplopia, drowsiness, ataxia, nausea, headaches, dry mouth, oedema, hyponatraemia, erythematous rash, sexual dysfunction.

Rare: agranulocytosis.

Atypical antipsychotics


Dopaminergic (D1–5) receptor antagonist, serotonergic (5-HT2A/C) receptor antagonist

Common: sexual dysfunction (hyperprolactinaemia).

Long term: movement disorders (e.g. tardive dyskinesia, akathisia, parkinsonism), increased risk of cardiovascular disease.

Rare: neuroleptic malignant syndrome




Dopaminergic (D2) and serotonergic (5-HT1A) receptor partial agonist

Common: weight gain, headache, agitation, insomnia, gastrointestinal effects, disinhibition.