Imigran (Sumatriptan)
Triptan for Acute Migraine and Cluster Headache Treatment
Quick Facts About Imigran
Key Takeaways About Imigran (Sumatriptan)
- First-line acute migraine treatment: Sumatriptan is the most extensively studied triptan, recommended by international guidelines (EHF, AHS, NICE) as first-line therapy for moderate-to-severe migraine attacks
- Fast-acting injection option: Subcutaneous injection provides relief within 10–15 minutes, making it the fastest-acting formulation for severe attacks or when nausea prevents oral administration
- Cardiovascular screening required: Imigran must not be used in patients with ischaemic heart disease, uncontrolled hypertension, previous stroke, or peripheral vascular disease
- Do not use for prevention: Imigran treats active migraine/cluster headache attacks only and should not be taken prophylactically to prevent attacks
- Avoid overuse: Using triptans more than 10 days per month can lead to medication-overuse headache (MOH), a condition where headaches become more frequent and difficult to treat
What Is Imigran and What Is It Used For?
Imigran contains sumatriptan, a selective serotonin (5-HT1B/1D) receptor agonist belonging to the triptan class of medicines. It is used for the acute treatment of migraine attacks (with or without aura) and cluster headaches (Horton's headache). Imigran is available as film-coated tablets and as a solution for subcutaneous injection.
Migraine is a complex neurological disorder characterised by recurrent episodes of moderate to severe headache, typically unilateral and pulsating in nature. Migraine attacks are often accompanied by nausea, vomiting, and heightened sensitivity to light (photophobia) and sound (phonophobia). According to the World Health Organization (WHO), migraine is the second leading cause of years lived with disability worldwide, affecting approximately 1 billion people globally. The condition is two to three times more common in women than in men, with a peak prevalence between the ages of 25 and 55.
Cluster headache, also known as Horton's headache, is one of the most painful conditions known to medicine. It presents as excruciating unilateral headache episodes centred around the eye or temple, lasting 15 minutes to 3 hours. Attacks occur in clusters, often at the same time each day, and may be accompanied by tearing, nasal congestion, and eyelid drooping on the affected side. Cluster headache affects approximately 0.1% of the population and is more common in men.
The symptoms of both migraine and cluster headache are believed to be caused, in part, by temporary dilation (widening) of blood vessels in the head. Sumatriptan exerts its therapeutic effect through multiple mechanisms. It selectively activates 5-HT1B receptors on intracranial blood vessels, causing vasoconstriction of the dilated cranial arteries and reducing blood flow to the meninges. Simultaneously, it activates 5-HT1D receptors on trigeminal nerve endings, inhibiting the release of vasoactive neuropeptides such as calcitonin gene-related peptide (CGRP) and substance P. This dual mechanism both reverses the vascular changes and interrupts the pain signalling cascade in the trigeminal system.
Sumatriptan was the first triptan to be developed, introduced by GlaxoSmithKline (then Glaxo) in 1991, and it represented a breakthrough in migraine treatment. Before triptans, patients relied primarily on ergotamine preparations and simple analgesics, which were often poorly tolerated or insuffective. Today, sumatriptan remains the most widely studied and prescribed triptan globally, with decades of real-world clinical evidence supporting its efficacy and safety profile.
It is important to take Imigran only after a migraine or cluster headache attack has started. The medication is not effective when taken during the aura phase (before headache onset) and should never be used as a preventive (prophylactic) treatment. For migraine prevention, your doctor may recommend different medications such as beta-blockers, topiramate, amitriptyline, or newer CGRP monoclonal antibodies.
What Should You Know Before Taking Imigran?
Before taking Imigran, your doctor must assess your cardiovascular risk factors. Sumatriptan is contraindicated in patients with ischaemic heart disease, previous heart attack, stroke or TIA, uncontrolled hypertension, peripheral vascular disease, and severe liver disease. It must not be used concurrently with ergotamine, other triptans, or MAO inhibitors.
Contraindications
You should not use Imigran if any of the following apply to you:
- Allergy to sumatriptan or any other ingredient in the product
- Heart problems including narrowed coronary arteries (ischaemic heart disease), chest pain (angina pectoris), or a previous heart attack (myocardial infarction)
- Circulatory problems in the legs that cause cramping pain when walking (peripheral arterial disease)
- Previous stroke (cerebrovascular accident) or transient ischaemic attack (TIA)
- Uncontrolled high blood pressure – Imigran may be used in patients with mild, treated hypertension under medical supervision
- Severe liver disease – sumatriptan is primarily metabolised by the liver, and impaired hepatic function can lead to dangerously elevated drug levels
- Concurrent use of ergotamine or ergot-type medications (e.g. methysergide, dihydroergotamine), or any other triptan/5-HT1 receptor agonist
- Concurrent or recent use of MAO inhibitors (monoamine oxidase inhibitors) – Imigran must not be used within 2 weeks of MAO inhibitor therapy
In very rare cases, serious cardiovascular events including heart attack and coronary artery vasospasm have occurred following sumatriptan use, even in patients without known heart disease. If you experience severe or persistent chest pain, tightness, or pressure after taking Imigran, seek immediate medical attention. Your doctor may wish to perform cardiovascular assessment before prescribing this medication, particularly if you have risk factors for heart disease.
Warnings and Precautions
Talk to your doctor or pharmacist before using Imigran if any of the following apply to you:
- Additional cardiovascular risk factors – particularly if you are a heavy smoker or use nicotine replacement therapy, if you are a man over 40 years of age, or if you are a post-menopausal woman. These factors increase the risk of undiagnosed coronary artery disease, and your doctor may wish to assess your cardiac function before starting treatment.
- History of seizures (epilepsy) or other factors that lower the seizure threshold, such as brain injury or alcohol dependence – sumatriptan should be used with caution, and more frequent monitoring may be required.
- Liver or kidney disease – dose adjustments may be necessary, and your doctor should monitor you more closely.
- Allergy to sulphonamide antibiotics – if you are allergic to sulphonamides, you may also be allergic to sumatriptan. Inform your doctor if you have any antibiotic allergies.
- Using SSRI or SNRI antidepressants – co-administration with sumatriptan carries a risk of serotonin syndrome, a potentially life-threatening condition. See the drug interactions section below.
- Frequent use of Imigran – using triptans or other acute headache medications more than 10 days per month can lead to medication-overuse headache (MOH). If you find yourself needing Imigran very frequently, consult your doctor, who may recommend stopping acute treatment and introducing preventive therapy instead.
If you experience chest pain or tightness after using Imigran, these sensations are usually transient and resolve quickly. They are thought to be caused by smooth muscle spasm in the oesophagus or chest wall rather than cardiac ischaemia. However, if the symptoms are severe, persistent, or worsening, seek immediate medical attention, as in rare cases they may indicate a cardiac event.
Pregnancy and Breastfeeding
The safety of sumatriptan during pregnancy has not been fully established. Data from pregnancy exposure registries involving several thousand pregnancies have not demonstrated an increased risk of congenital malformations, but the evidence is insufficient to definitively confirm safety. If you are pregnant, think you might be pregnant, or are planning to become pregnant, discuss the use of Imigran with your doctor. Your doctor will weigh the potential benefits against the risks and may recommend alternative approaches to managing migraine during pregnancy.
Sumatriptan is excreted in breast milk. To minimise infant exposure, you should avoid breastfeeding for 12 hours after using Imigran. Any breast milk expressed during this 12-hour period should be discarded and not given to your infant. Some breastfeeding women have reported transient breast pain or nipple pain following sumatriptan use; this typically resolves within 3 to 12 hours.
Driving and Operating Machinery
Both migraine symptoms and sumatriptan itself can cause drowsiness, dizziness, and fatigue that may impair your ability to drive or operate machinery safely. During a migraine attack, you should refrain from driving regardless of whether you have taken medication. After taking Imigran, wait until you feel fully recovered before driving or performing tasks that require alertness and concentration. You are legally responsible for assessing your own fitness to drive.
How Does Imigran Interact with Other Drugs?
Imigran has several clinically significant drug interactions. It must not be used with ergotamine, other triptans, or MAO inhibitors. Caution is required when using Imigran alongside SSRI/SNRI antidepressants due to the risk of serotonin syndrome. Always inform your doctor of all medications, including herbal products.
Drug interactions with sumatriptan can range from potentially life-threatening (serotonin syndrome, coronary vasospasm) to moderate increases in side effects. Understanding these interactions is essential for safe use. Tell your doctor or pharmacist about all medicines you take, including prescription medications, over-the-counter products, and herbal remedies.
Major Interactions
| Drug / Class | Risk | Management |
|---|---|---|
| Ergotamine, dihydroergotamine, methysergide | Additive coronary vasoconstriction; risk of prolonged vasospasm and ischaemia | Stop ergotamine at least 24 hours before Imigran. Wait at least 6 hours after Imigran before taking ergotamine. |
| Other triptans (naratriptan, rizatriptan, zolmitriptan, eletriptan, almotriptan, frovatriptan) | Additive serotonergic effects and coronary vasoconstriction | Do not use concurrently. Wait at least 24 hours between different triptans. |
| MAO inhibitors (moclobemide, phenelzine, tranylcypromine, selegiline) | Reduced sumatriptan metabolism; increased plasma levels; serotonin toxicity | Contraindicated. Do not use within 2 weeks of MAO inhibitor therapy. |
| SSRIs (fluoxetine, sertraline, paroxetine, citalopram, escitalopram) | Serotonin syndrome: agitation, confusion, sweating, hallucinations, rapid heartbeat, muscle twitching, tremor | Use with caution. Monitor for signs of serotonin syndrome. Seek immediate medical attention if symptoms develop. |
| SNRIs (venlafaxine, duloxetine, desvenlafaxine) | Serotonin syndrome (same as SSRIs above) | Use with caution under medical supervision. Monitor carefully for serotonergic symptoms. |
Other Interactions
| Drug / Substance | Effect | Advice |
|---|---|---|
| St John’s Wort (Hypericum perforatum) | Increased serotonergic activity; higher risk of side effects | Avoid concurrent use. Inform your doctor if you use herbal supplements. |
| Lithium | Additive serotonergic effects; theoretical risk of serotonin syndrome | Monitor for serotonergic symptoms when co-administered. |
| Paracetamol, NSAIDs (ibuprofen, naproxen) | No clinically significant interaction; may improve efficacy | Generally safe to combine. Sumatriptan + naproxen is an established combination. |
Serotonin syndrome is a potentially life-threatening condition that can occur when sumatriptan is combined with other serotonergic drugs. Symptoms include restlessness, agitation, confusion, rapid heartbeat, dilated pupils, loss of coordination, muscle twitching or rigidity, heavy sweating, diarrhoea, and in severe cases, high fever and seizures. If you experience any of these symptoms after taking Imigran, seek emergency medical attention immediately.
What Is the Correct Dosage of Imigran?
The standard adult dose is one 50 mg tablet taken orally at the onset of a migraine attack, or one 6 mg subcutaneous injection. Imigran should only be used when a migraine or cluster headache attack has begun – it is not for preventive use. Do not exceed the maximum recommended dose within a 24-hour period.
Always use Imigran exactly as your doctor has instructed. If you are unsure, consult your doctor or pharmacist. The dose and formulation will depend on the type of headache being treated, the severity of your attacks, your response to treatment, and any other medical conditions you may have.
Adults (18 to 65 years)
Oral Tablets – Migraine
Standard dose: 50 mg taken as soon as the migraine headache begins. Some patients may require 100 mg.
If the headache returns: A second dose may be taken after at least 2 hours, provided the first dose gave some initial relief.
Maximum dose: 300 mg in 24 hours.
If the first dose has no effect: Do not take a second dose for the same attack. You may take a different type of pain reliever. Consult your doctor if Imigran is consistently ineffective.
Subcutaneous Injection – Migraine and Cluster Headache
Standard dose: One injection of 6 mg (0.5 ml of 12 mg/ml solution) administered subcutaneously, typically into the outer thigh.
If symptoms return: A second injection may be given after at least 1 hour.
Maximum dose: Two injections (12 mg total) in 24 hours.
If the first injection has no effect: Do not give a second injection for the same attack.
| Formulation | Single Dose | Re-dose Interval | Max in 24 Hours |
|---|---|---|---|
| Tablets (oral) | 50 mg (or 100 mg) | At least 2 hours | 300 mg |
| Injection (SC) | 6 mg (0.5 ml) | At least 1 hour | 12 mg (2 injections) |
Children and Adolescents
Imigran is not recommended for use in patients younger than 18 years of age. The safety and efficacy of sumatriptan in children and adolescents have not been sufficiently established. If your child suffers from migraine, consult a paediatric neurologist for appropriate treatment options.
Elderly Patients (over 65 years)
There is limited clinical experience with sumatriptan in patients over 65 years of age. Imigran is generally not recommended for this age group due to insufficient safety data and the higher prevalence of cardiovascular risk factors in older adults. If you are over 65, your doctor should carefully assess the benefit–risk balance before prescribing Imigran.
Patients with Liver Disease
Sumatriptan is metabolised primarily by the liver. Patients with mild to moderate hepatic impairment may be more sensitive to sumatriptan and should use lower doses under medical supervision. Imigran is contraindicated in severe liver disease, as reduced hepatic clearance could lead to dangerously elevated plasma levels of the drug.
Missed Dose
Imigran is used only when needed to treat an acute attack – there is no regular dosing schedule, so the concept of a “missed dose” does not apply. Do not take Imigran to make up for attacks that were not treated.
Overdose
Taking more than the recommended dose of sumatriptan can cause serious adverse effects. Oral overdose with doses exceeding 400 mg has not been associated with additional side effects beyond those described at therapeutic doses. However, the subcutaneous injection carries a higher risk of toxicity if overdosed. Symptoms of overdose may include extreme drowsiness, tremor, redness, and reduced breathing rate. If you suspect an overdose, contact your doctor or local poison control centre immediately.
What Are the Side Effects of Imigran?
Like all medicines, Imigran can cause side effects, although not everybody gets them. The most common side effect with the injection is temporary pain or irritation at the injection site (up to 50% of users). Other common side effects include tingling, warmth, flushing, dizziness, drowsiness, and a sensation of heaviness or pressure in the chest, throat, or limbs.
Some side effects reported with sumatriptan may also be caused by the migraine attack itself, making it important to distinguish between drug effects and symptoms of the underlying condition. Most side effects are mild to moderate in severity and resolve quickly without treatment. However, certain rare side effects require immediate medical attention.
Signs of an allergic reaction: skin rash, hives (itchy raised welts), wheezing, swelling of the eyelids, face or lips, or collapse. Signs of a heart attack: severe or persistent chest pain, tightness or heaviness that does not resolve within a few minutes. Signs of serotonin syndrome (if using SSRIs/SNRIs): restlessness, confusion, sweating, hallucinations, rapid heartbeat, muscle rigidity, tremors.
Very Common
- Transient pain, stinging, or irritation at injection site (up to 50% of patients using the injection formulation)
Common
- Tingling, numbness, or unusual sensations (paraesthesia) – often felt in the hands, feet, or face
- Sensation of warmth or cold
- Feeling of heaviness, pressure, or tightness in the chest, throat, neck, or limbs (usually transient)
- Flushing (warmth and redness of the skin)
- Dizziness and light-headedness
- Drowsiness and fatigue
- Nausea and vomiting (may also be part of the migraine itself)
- Muscle aching (myalgia)
- Transient increase in blood pressure
- Shortness of breath (dyspnoea)
Rare
- Chest pain (non-cardiac)
Very Rare / Frequency Not Known
- Hypersensitivity reactions (rash, hives, anaphylaxis)
- Seizures and tremors
- Visual disturbances (flickering, blurred vision, double vision, partial vision loss – may also be migraine-related)
- Cardiac arrhythmias (slow or fast heartbeat, palpitations)
- Angina pectoris or myocardial infarction (heart attack)
- Raynaud’s phenomenon (pale or blue discolouration of fingers, toes, ears, or nose)
- Ischaemic colitis (abdominal pain with bloody diarrhoea)
- Changes in liver function tests
- Neck stiffness and muscle spasm
- Feeling of anxiety
- Difficulty swallowing (dysphagia)
- Excessive sweating
- Joint pain (arthralgia)
If you experience chest pain, tightness, or pressure after using Imigran, these symptoms are usually brief and not cardiac in origin. They are believed to result from smooth muscle spasm and are among the most commonly reported triptan effects. However, because coronary vasospasm cannot be entirely excluded without investigation, you should discuss persistent or concerning chest symptoms with your doctor promptly.
Using any acute headache medication – including triptans, analgesics, or combination painkillers – on more than 10 days per month for 3 or more months can lead to medication-overuse headache. This is a condition where headaches paradoxically become more frequent and severe. If you suspect MOH, consult your doctor. Treatment typically involves gradual withdrawal of the overused medication under medical supervision, often with introduction of preventive therapy.
How Should You Store Imigran?
Store Imigran at or below 30°C (86°F) in the original packaging. Keep out of the sight and reach of children. Do not use the medication after the expiry date printed on the carton.
Proper storage of medication ensures that it retains its full potency and remains safe to use throughout its shelf life. Imigran should be stored in a dry place, away from direct sunlight and excessive heat. Do not freeze the injection solution. Keep tablets in their blister packaging until ready to use to protect them from moisture.
Check the expiry date on the packaging before each use. The expiry date refers to the last day of the stated month. Do not use Imigran if the solution appears cloudy, discoloured, or contains visible particles. Used injection pens, cartridges, and expired tablets should be returned to a pharmacy for safe disposal. Do not dispose of medications via household waste or down the drain, as this can harm the environment.
What Does Imigran Contain?
The active substance in Imigran is sumatriptan succinate. Each injection delivers 6 mg of sumatriptan (as sumatriptan succinate) in 0.5 ml solution. Tablets contain 50 mg of sumatriptan. Excipients vary by formulation.
Injection (12 mg/ml solution)
Each pre-filled cartridge (0.5 ml) contains sumatriptan succinate equivalent to 6 mg sumatriptan. The other ingredients are sodium chloride and water for injections. The injection is supplied in a kit containing an auto-injector pen (Imigran pen) and cartridges. Refill packs with additional cartridges are also available.
Film-Coated Tablets
Each film-coated tablet contains sumatriptan succinate equivalent to 50 mg sumatriptan. The tablets also contain inactive ingredients (excipients) such as lactose monohydrate, microcrystalline cellulose, croscarmellose sodium, magnesium stearate, and a film coating.
Imigran injection contains less than 1 mmol (23 mg) sodium per cartridge, meaning it is essentially sodium-free. This is relevant for patients on a sodium-restricted diet.
The needle shield inside the plastic cartridge housing of the Imigran injection may contain natural rubber latex. If you have a known latex allergy, inform your doctor before using this product.
Frequently Asked Questions
Imigran (sumatriptan) is used for the acute treatment of migraine attacks, with or without aura, and cluster headaches (Horton's headache). It belongs to the triptan class of medications and works by constricting dilated blood vessels in the brain and blocking pain signal transmission in the trigeminal nerve. It is not a preventive medication – it should only be taken once an attack has started.
The onset of action depends on the formulation. The subcutaneous injection works fastest, typically providing meaningful headache relief within 10–15 minutes. Oral tablets generally begin to work within 30–60 minutes. For the best results, Imigran should be taken as early as possible once the headache phase of a migraine has begun. Taking it during the aura phase (before headache onset) does not improve its effectiveness.
Yes, Imigran can generally be taken alongside simple analgesics such as paracetamol (acetaminophen) or NSAIDs like ibuprofen and naproxen. There are no clinically significant interactions between sumatriptan and these medications. In fact, the combination of sumatriptan with naproxen has been shown in clinical trials to be more effective than either drug alone and is available as a fixed-dose combination product in some countries. However, always check with your doctor or pharmacist before combining medications.
For tablets, you may take a second dose after at least 2 hours if the headache returns, up to a maximum of 300 mg in 24 hours. For injections, a second dose can be given after at least 1 hour, with a maximum of 12 mg (two injections) in 24 hours. Importantly, if the first dose does not work at all for a given attack, do not take a second dose for that same attack. Chronic overuse of triptans (more than 10 days per month) can cause medication-overuse headache.
If the first dose of Imigran does not relieve your migraine, do not take a second dose for the same attack. You may try a different type of pain reliever instead (such as an NSAID or paracetamol). If the headache initially improved but then returned, you may take a second dose after the recommended waiting period. If Imigran consistently fails to provide relief across multiple attacks, speak with your doctor. You may benefit from trying a different triptan (such as rizatriptan or zolmitriptan) or an alternative class of acute migraine treatment.
The safety of Imigran in pregnancy has not been fully established, although pregnancy registry data have not shown an increased risk of birth defects to date. Always consult your doctor before using Imigran during pregnancy. When breastfeeding, you should wait at least 12 hours after using Imigran before nursing your baby. Any expressed breast milk during this 12-hour period should be discarded. Your doctor can help you weigh the benefits and risks for your individual situation.
References
This article is based on evidence from international medical guidelines, systematic reviews, and peer-reviewed clinical research. All sources follow the GRADE evidence framework and represent Level 1A evidence where available.
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- Ferrari MD, Roon KI, Lipton RB, Goadsby PJ. Oral triptans (serotonin 5-HT(1B/1D) agonists) in acute migraine treatment: a meta-analysis of 53 trials. Lancet. 2001;358(9294):1668–1675.
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About Our Medical Editorial Team
This article has been written and reviewed by licensed specialist physicians with expertise in neurology, headache medicine, and clinical pharmacology. Our medical editorial team follows international guidelines from the European Headache Federation (EHF), American Headache Society (AHS), and the International Headache Society (IHS). All content adheres to the GRADE evidence framework and is based on Level 1A evidence where available.
Written by iMedic Medical Editorial Team – specialists in neurology, headache medicine, and clinical pharmacology with documented academic credentials and clinical experience.
Reviewed by iMedic Medical Review Board – an independent panel of board-certified physicians who verify all content against current international evidence-based guidelines.
Conflict of interest declaration: iMedic has no commercial affiliations with pharmaceutical companies. All content is independently produced without industry funding or influence. We receive no payments, grants, or other financial support from manufacturers of sumatriptan or competing migraine treatments.