Lithium: The Dispensing Safety Checklist

📋 First Dispense Essentials

Mandatory items to issue

• Ensure the patient has all three NHS lithium resources: the alert card, the information booklet, and the monitoring booklet. These must be provided at the point of prescribing and are available to order from NHS England. Replacements can be sourced via the SPS guidance on accessing high-risk medicine resources.²
• Confirm the prescription is written by brand name and formulation. Record the brand, formulation, and dose in the pharmacy medication record.
• Before starting lithium, the prescriber or specialist should have confirmed: baseline BMI, eGFR, U&Es, FBC, thyroid function, serum calcium, and pregnancy status where relevant. An ECG is required if the patient has cardiovascular disease or risk factors. Lithium initiation and target-range setting are specialist-led under shared-care arrangements; confirm that baseline testing has been completed and documented before dispensing the first supply.^1,2

Baseline clinical checks

• Before starting lithium (pre-initiation): confirm BMI, eGFR, U&Es, FBC, thyroid function, serum calcium, and pregnancy status where relevant. Arrange an ECG if the patient has cardiovascular disease or risk factors. These checks are completed by the specialist or prescriber under shared-care arrangements.
• After starting lithium or following a dose change: the first lithium level is checked at one week, then weekly until stable. Levels should be taken approximately 12 hours after the last dose (12-hour trough level). For people prescribed lithium for the first time, NICE recommends aiming for 0.6 to 0.8 mmol/L.¹ A higher target of 0.8 to 1.0 mmol/L may be considered for relapse or persistent subthreshold symptoms under specialist direction.
• Renal function: lithium is primarily renally excreted. Even mild renal impairment reduces clearance and increases the risk of accumulation and toxicity. Dose adjustment is required in renal impairment. Patients should be advised to report renal dysfunction symptoms including polyuria (passing more urine than usual) and polydipsia (excessive thirst).³
• Thyroid function: long-term lithium can cause hypothyroidism in a substantial minority of patients. Symptoms can be subtle and may be attributed to the underlying psychiatric condition if monitoring is not maintained. U&Es and FBC are also monitored regularly as part of shared-care arrangements.
• Calcium: lithium can cause hypercalcaemia over time. Serum calcium is checked routinely every 6 months. If hypercalcaemia is detected, parathyroid function should be investigated.
• Weight: checked at least annually. Unexplained weight loss may indicate worsening depression; weight gain may indicate developing hypothyroidism.

Key risks and lifestyle traps

• Lithium brands are not bioequivalent and are not interchangeable. Tablet brands (lithium carbonate) include Priadel, Camcolit, and Liskonum. Liquid brands (lithium citrate) include Priadel liquid and Li-Liquid. Switching between brands or formulations requires prescriber review and close monitoring of lithium levels.
• Key drug interactions that increase lithium levels and risk of toxicity: ACE inhibitors (angiotensin-converting enzyme inhibitors), angiotensin receptor blockers, thiazide diuretics, loop diuretics, COX-2 inhibitors, and non-steroidal anti-inflammatory drugs (NSAIDs). Check the patient record for any of these at every dispense.⁴
• Sudden changes in salt intake can alter lithium levels. Low-salt diets, dehydration, vomiting, diarrhoea, and heavy sweating can all increase toxicity risk. Regular use of sodium-containing over-the-counter products (effervescent tablets, antacids, health salts) should be checked with the pharmacist or prescriber before starting.
• Lithium carbonate and lithium citrate are not dose-equivalent on a simple milligram-to-milligram basis. Check the formulation strength carefully if any query about switching arises.
• Dehydration raises lithium levels rapidly. Causes include vomiting, diarrhoea, fever, excess heat, and some medicines including diuretics. Patients should be counselled to maintain consistent fluid and salt intake and to contact their prescriber if they become unwell.
• Neurotoxicity can occur even when plasma lithium levels are within the target range, particularly in frail or older patients. The absence of a raised level does not rule out toxicity.

First dispense script

🔄 Repeat Dispense Screen

Mandatory documentation

• Record the brand name, formulation, and dose dispensed on every occasion. If a different brand is supplied for any reason, document this and the prescriber agreement obtained.
• Record the date of the most recent lithium level and whether monitoring is current against the patient's agreed schedule. Flag any overdue monitoring and document any action taken.

Ongoing clinical checks

• Lithium level: during the first year of treatment, levels are checked every 3 months. After the first year, stable low-risk patients are usually monitored every 6 months.¹ Higher-risk patients should continue on at least 3-monthly monitoring. Higher-risk groups include: older patients, those on interacting medicines (ACE inhibitors, ARBs, NSAIDs, loop or thiazide diuretics), those with renal, thyroid, or calcium problems, poor adherence or symptom control, a recent level at or above 0.8 mmol/L, and women who are pregnant or planning pregnancy.
• If monitoring appears overdue against the patient's agreed schedule, check the patient's monitoring booklet or PMR, and ask the patient. If results are unavailable or monitoring cannot be confirmed, contact the prescriber or mental health team urgently. Make a documented professional judgement — avoid unplanned interruption of treatment unless lithium toxicity is suspected. Do not automatically withhold supply in a way that causes abrupt withdrawal.²
• If the patient has no monitoring booklet, check the pharmacy medication record or Summary Care Record where available. Ask the patient when they last had a blood test and who arranged it. If uncertain, contact the GP or mental health team and document the outcome before dispensing.
• Blood samples for lithium should be taken approximately 12 hours after the last dose (12-hour trough). Check the monitoring booklet for the timing of the last test result and when it is next due.³
• Renal function, thyroid function, and calcium are usually monitored every 6 months, though higher-risk patients may need more frequent testing. If overdue, advise the patient to book a blood test and inform the prescriber.
• Check for new interacting medicines at every dispense, particularly ACE inhibitors, angiotensin receptor blockers, NSAIDs, COX-2 inhibitors, loop diuretics, and thiazide diuretics.
• Confirm the brand and formulation match the previous supply. Do not switch without prescriber agreement.

Ask the patient at the counter

• "Have you had your lithium blood tests recently, and are they up to date?"
• "Have you started any new medicines, including anything bought without a prescription?"
• "Have you had any sickness, diarrhoea, dehydration, or changes in fluid intake recently?"
• "Have you noticed any shakiness, confusion, or unusual symptoms since your last supply?"

Lifestyle and surgical alerts

• Take lithium at the same time each day (usually in the evening to allow 12 hours between the last dose and the blood test). Missed doses should not be doubled up.
• Maintain consistent fluid intake and salt intake. Dehydration and low-salt diets both increase lithium levels. Advise extra caution during hot weather, illness, or exercise.
• Avoid ibuprofen and other non-steroidal anti-inflammatory drugs (NSAIDs) unless specifically agreed with the prescriber. These raise lithium levels.
• Women of childbearing potential should use effective contraception and discuss the risks with their specialist. Lithium is associated with cardiac malformations in the fetus, particularly Ebstein anomaly, though the absolute risk is low.
• Driving and operating machinery: lithium may cause drowsiness, impaired coordination, or visual disturbance, particularly during dose changes or when levels are high.
• Report any new or worsening symptoms to the prescriber promptly: increased thirst or urination may indicate renal effects; weight gain, tiredness, and feeling cold may indicate hypothyroidism.

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