Mood stabilisers are used in bipolar disorder to reduce the frequency and severity of episodes. The group is less uniform than the name suggests: it includes lithium, several medicines originally developed for epilepsy, and some antipsychotics. Their side effects and monitoring differ substantially, so knowing which one you are on matters.
What they share: most need blood monitoring, none should be stopped abruptly, and pregnancy needs planning in advance rather than reacting to.
Common side effects and early adjustment effects
- Lithium. Fine hand tremor, increased thirst and urination, nausea, metallic taste, weight gain. See lithium side effects.
- Sodium valproate. Nausea, drowsiness, tremor, weight gain, hair thinning. See sodium valproate side effects.
- Lamotrigine. Headache, dizziness, double vision, nausea. Generally weight-neutral. See lamotrigine side effects.
- Antipsychotics used as mood stabilisers. Sedation, weight gain and metabolic change. See antipsychotic side effects.
Serious mood, behaviour or physical symptoms to take seriously
Each has a signature warning worth memorising for the one you take:
- Lithium toxicity. A coarse tremor, vomiting, severe diarrhoea, slurred speech, unsteadiness, drowsiness or confusion. A medical emergency, and often triggered by dehydration, a stomach bug, hot weather or starting an anti-inflammatory. See lithium toxicity symptoms.
- Lamotrigine rash. Any rash in the first weeks needs same-day advice, because of a rare but severe skin reaction. This is why the dose is increased slowly.
- Valproate. Persistent vomiting, marked tiredness, abdominal pain or yellowing of the eyes, which can indicate liver problems, and severe abdominal pain suggesting pancreatitis.
- Antipsychotics. High fever with muscle stiffness and confusion, and new involuntary movements of the face or tongue.
Also seek urgent help for new or worsening thoughts of self-harm, or a switch into elevated mood with reduced need for sleep.
Sexual, sleep, weight and emotional side effects
Weight gain is common with lithium, valproate and several antipsychotics, and is one of the main reasons people stop. Raise it early, since it is easier to address before it accumulates and there may be alternatives with lower rates.
Some people describe feeling emotionally flattened or less creative on mood stabilisers. This is worth discussing rather than accepting, since it sometimes reflects a dose higher than necessary.
Interactions, alcohol, pregnancy and other risk factors
Pregnancy needs planning in advance. Valproate carries serious risks of birth defects and developmental problems and is not used in those who could become pregnant except under strict conditions. Lithium requires specialist input. Lamotrigine levels change during pregnancy. None of these should be stopped abruptly on discovering a pregnancy; contact your specialist urgently instead. See mental health medication in pregnancy.
Interactions to know: anti-inflammatories, diuretics and some blood pressure medicines raise lithium levels; valproate substantially raises lamotrigine levels; hormonal contraception can lower lamotrigine levels. Alcohol contributes to dehydration and destabilises mood. See mental health medication and alcohol.
What to ask your doctor before changing dose or stopping
Never stop a mood stabiliser abruptly. Relapse risk is substantial, and for medicines also used in epilepsy, stopping can trigger seizures.
- What blood tests do I need, and when are they due?
- What are the warning signs specific to my medicine?
- What should I do if I get a stomach bug or become dehydrated?
- Which painkillers are safe for me?
- What should I know if I am planning a pregnancy?
Related mental health medication guides
- Mental health medication side effects
- Should I stop my mental health medication
- When to call a doctor
- Psychiatric medication side effects
- Report a side effect in South Africa
See also bipolar medication side effects.
Medical Disclaimer: This content is for informational and educational purposes only and does not constitute medical diagnosis, prescription, or professional advice. Always read the patient information leaflet and consult a qualified doctor or pharmacist regarding any medicine or health concern.