Flunarizine

Pronunciation: floo-NAR-i-zeen.

Generic name: flunarizine
Brand names: Sibelium
Drug class: Calcium channel blocker (used for migraine prophylaxis)
Form: Tablet (5 mg)
Route: Oral
Legal status: Prescription-only medicine in Ireland; not licensed in the United Kingdom. US FDA approval status could not be confirmed in this pass and should not be assumed either way.

Availability and supply rules vary by country

Trade names by country: India

What flunarizine is and how it works

Flunarizine is a calcium channel blocker used to prevent migraine attacks (migraine prophylaxis) rather than treat an attack once it has started. (2)

It is taken once daily, usually at night, and is generally used for a limited period (up to about 6 months) rather than indefinitely. It has specific contraindications related to mood and movement disorders that must be checked before starting.

Mechanism of action: how flunarizine works

Flunarizine is a calcium channel blocker that reduces arterial and arteriolar smooth-muscle spasm; its exact mechanism in migraine prevention is not detailed in the source reviewed. (1)

What flunarizine is used for

Migraine prophylaxis (prevention)

Used to reduce the frequency of migraine attacks in adults. It is a preventive treatment, not a treatment for an attack already in progress. (2)

Before taking flunarizine

Do not take / not appropriate for

Do not take flunarizine if you currently have depression, or if you have a history of recurrent depression. (all products) (2)
Do not take flunarizine if you have Parkinson's disease or another condition causing tremor, stiffness, or slowed movement (an extrapyramidal disorder). (all products) (2)

Tell your clinician about

Any personal or family history of depression.
Any history of Parkinson's disease, tremor, or other movement disorder.
Your age, since older adults are usually started on a lower dose.
Pregnancy, plans for pregnancy, or breastfeeding.
Every other medicine you take.

(2)

How to take flunarizine

Take exactly as prescribed, usually once daily at night.
Once your migraines respond to treatment, your prescriber may have you take 2 drug-free days each week.
Treatment is generally limited to about 6 months; do not continue beyond this or restart after stopping without your prescriber's advice.
Do not change your dose or stop taking flunarizine without talking to your prescriber first.

(2)

Procedures and treatment changes

Tell the treating team before surgery, procedures, or any medicine change. Do not alter treatment without the responsible clinician. (1) (2)

Missed dose

If you forget a dose, do not take the missed dose. Wait and take your next dose at the usual time, then continue as normal. Do not take a double dose to make up for a missed one.

Overdose

If you, or anyone else, takes more flunarizine than directed, contact a doctor or local hospital immediately. (1)

Side effects

Weight gain is a very commonly reported effect. Mood and movement-related effects need particular attention given this medicine's specific contraindications.

Weight gain

What to notice: A very commonly reported effect (affects more than 1 in 10 people).

What to do: Discuss with your prescriber if significant or concerning. (1)

Increased appetite, blocked or runny nose, feeling low or depressed, sleep problems or sleepiness, nausea, constipation, stomach ache or digestive problems, muscle aches, breast pain, menstrual irregularities, fatigue

What to notice: Common effects (affect fewer than 1 in 10 people).

What to do: Tell your prescriber if troublesome or persistent. (1)

Anxiety, restlessness, low energy, disorientation, palpitations, low blood pressure, dry mouth, excessive sweating, swelling of hands/legs/feet, low libido, or mild allergic-type skin reaction (rash, flushing, hives)

What to notice: Uncommon effects (affect fewer than 1 in 100 people).

What to do: Tell your prescriber if these occur, especially if persistent or bothersome. (1)

New low mood or movement symptoms

What to notice: New or worsening depression, or new tremor, stiffness, or slowed movement.

What to do: Contact your prescriber promptly; a clinician will decide whether flunarizine needs to be stopped. (1)

Tingling/numbness or tinnitus

What to notice: Tingling or numbness in the hands or feet, or buzzing/hissing/whistling/ringing in the ears.

What to do: Tell your prescriber as soon as possible; you may need medical treatment. (1)

Extrapyramidal (movement) symptoms

What to notice: Jerky movements, slowness, muscle stiffness or rigidity, trembling, or unusual twitching of the tongue, face, mouth, jaw, or throat.

What to do: Tell your prescriber as soon as possible; an additional medicine may be needed to manage this, and a clinician will decide whether flunarizine needs to be stopped. (1)

Severe allergic reaction

What to notice: Swelling of the face, lips, mouth, tongue, or throat, which may cause difficulty swallowing or breathing.

What to do: Seek emergency medical help immediately. (1)

Serious warnings

Depression or movement disorder developing during treatment — urgent

Symptoms: New or worsening low mood, or new tremor, muscle stiffness, or slowed movement.

Action: Contact your prescriber promptly. These are recognised risks of this medicine, particularly with longer use, and the prescriber will decide whether to continue or stop treatment. (1)

Severe allergic reaction — emergency

Symptoms: Swelling of the face, lips, mouth, tongue, or throat, which may cause difficulty swallowing or breathing.

Action: Seek emergency medical help immediately. (1)

Interactions

Medicine or test	Effect	Action
Tranquillisers or sleep medicines (medicines for anxiety or to help you sleep)	May increase drowsiness when combined with flunarizine.	Tell your prescriber and pharmacist about all other medicines you take, including tranquillisers or sleep aids. (1)
Oral contraceptives	May cause secretion of breast milk during the first two months of flunarizine treatment.	Tell your prescriber if you are taking an oral contraceptive and notice this effect. (1)
Medicines to control high blood pressure	Your prescriber may need to adjust the dose of your blood-pressure medicine while you take flunarizine.	Tell your prescriber about all blood-pressure medicines you take. (1)
Alcohol	The combined effect of flunarizine and alcohol can increase drowsiness.	Avoid drinking alcohol while taking flunarizine. (1)

Pregnancy, breastfeeding, kidney/liver function, age

Older adults

Adults 65 and older are usually started on a lower dose (5 mg daily) compared with younger adults (10 mg daily). (2)

Depression or movement disorder history

This medicine is not suitable if you currently have depression, have had recurrent depression, or have Parkinson's disease or another movement disorder. (2)

Pregnancy and breastfeeding

Flunarizine is not recommended during pregnancy; talk to your prescriber before use if you are pregnant or trying to become pregnant. Do not breastfeed while taking flunarizine, since small amounts pass into breast milk. (1)

Driving and using machines

Flunarizine can make you drowsy. Do not drive or use tools or machines if this happens. (1)

Monitoring

Before starting

Confirm the migraine diagnosis and screen for current or past depression and for Parkinson's disease or other movement disorders.
Confirm age, since dosing differs for adults under and over 65.

During treatment

Watch for new or worsening low mood, tremor, or movement changes.
Reassess after up to about 6 months of treatment; do not continue indefinitely without the prescriber's review.

(2)

Storage

Do not store above 25°C (77°F). Keep out of the sight and reach of children. Do not use after the expiry date printed on the packaging.

Study the drug class: Triptans and migraine agents

Professional information

Clinician-facing context only. Sourced from the Ireland-authorised HPRA/Janssen patient leaflet; verify against the current SmPC for exact prescribing detail.

Ireland

Indication: Migraine prophylaxis

Dose summary: Adults 18-64: 10 mg (two 5 mg tablets) once daily in the evening, after a meal. Adults 65+: 5 mg (one tablet) once daily in the evening. Not recommended in children. Maintenance with 2 consecutive drug-free days per week once responding. Maximum treatment duration approximately 6 months; complete break required, with restart to be decided by the prescriber if migraine relapses.

Renal context: Not established in the source reviewed for this dossier. (1)

Mechanism of action

Hepatic guidance

Not established in the source reviewed for this dossier.

Overdose note

The patient leaflet directs contacting a doctor or local hospital immediately for suspected overdose; no specific antidote or overdose-management detail is given in this source. (1)

Frequently asked questions

What is flunarizine used for?

flunarizine is prescribed for approved indications. Always follow your healthcare provider's guidance.

What are the side effects of flunarizine?

Common side effects may include gastrointestinal symptoms and headache. Serious side effects require immediate medical attention.

Can I take flunarizine with other medications?

Always inform your healthcare provider about all medications you are taking, including over-the-counter products and supplements.

What is the mechanism of action of flunarizine?