Imitrex: Uses, Dosage, Side Effects & More

By Jennifer Nadel, MD
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June 29, 2022

Imitrex (sumatriptan) is a type of medication called a selective serotonin receptor agonist, commonly called a triptan.

It is most commonly prescribed to treat migraines and severe headaches. 

In this article, I’ll explain what Imitrex is, how it works, potential drug interactions, cautionary warnings, and some alternatives to Imitrex or sumatriptan.

I’ll also cover when you should consult a doctor.

Imitrex Dosage Guide

Imitrex comes in oral tablets as well as an injection.

Imitrex tablets are available in 25 mg, 50 mg, and 100 mg doses. Although the 50 mg or 100 mg tablets may be stronger, there is evidence that doses greater than 50 mg don’t produce better or faster effects.

Anytime you take a dose of Imitrex, you should wait at least two hours before taking another dose.

The maximum oral dose in 24 hours is 200 mg.

How to use Imitrex

Imitrex is prescribed for the acute treatment of migraines with or without the presence of auras.

To use Imitrex, you must have a prescription from a doctor, and you must have a clear diagnosis to be treated.

If you are prescribed Imitrex, take one dose at the first sign of a migraine or headache.

Acute treatment refers to a single dosage taken for a non-continuous situation. This is not a medication you take daily, but one you would take as needed at a migraine or headache’s start.

Imitrex is not used for preventing headaches or migraines.

Imitrex has also not been tested for safety of treating more than four headaches per 30-day period.

If you have been prescribed Imitrex (sumatriptan) and are having a migraine, your doctor might ask you to take the first tablet in the office so they can watch for any adverse reactions.

Wait at least two hours after taking an Imitrex dose before taking another when treating a headache or migraine.

Keep Imitrex tablets in a cool or room temperature space that’s out of reach of children. Keep your medication in the same container it came in, especially if it is child-resistant.

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How Fast Does Imitrex Work?

When taking Imitrex (sumatriptan) for migraines or headaches, you should wait at least two hours before considering an additional dose.

In studies, most patients report either no or mild headache pain two to four hours after taking the medication.

Some (10%) reported reduced pain as soon as 30 minutes after taking the medication.

For study participants who experienced migraines with associated nausea or sensitivity to light or sound, taking Imitrex reduced these symptoms after two hours.

Imitrex Side Effects

Common side effects found in clinical trials of Imitrex include:

  • Flushing or blushing in the face
  • Tingling sensations
  • Warm or cold sensations
  • Drowsiness
  • Weakness
  • Dizziness
  • Upset stomach or nausea
  • Diarrhea
  • Muscle cramping
  • Increased blood pressure

If these symptoms persist or are severe, contact your doctor.

Some side effects are more severe than others.

These can be indicative of an allergic reaction, drug interaction, or other dangerous response.

If you experience any of the following serious side effects, call 9-1-1 for emergency medical help immediately:

  • Pain, tightness, or pressure in your chest/throat/neck
  • Redness, swelling, or itching in the eyes/face/lips/throat
  • Slowed or difficulty speaking
  • Breaking out in a cold sweat
  • Numbness in the arm/leg
  • Bloody diarrhea
  • Sudden or severe stomach pain
  • Vomiting
  • Sudden weight loss
  • Difficulty breathing or swallowing
  • Rash or hives
  • Changes in vision
  • Seizures

What happens when you miss a dose

Since Imitrex is not made to be taken every day, it is safe if you don’t take it every time you experience a headache or migraine.

There are no consequences for skipping the medication if you do not want to take it.

If you need to dispose of Imitrex or other medications, bring them back to a doctor or pharmacy rather than throwing them in the garbage or flushing them down a toilet.

This prevents animals from finding or eating the medicine, and keeps it out of any water systems.

Drug Interactions with Imitrex

Imitrex has dangerous side effects and drug interactions when mixed with the following medications:

  • Ergot-containing drugs: Taking Imitrex within 24 hours of taking an ergot-containing drug (such as dihydroergotamine or methysergide) is not recommended due to the potential for vasospastic reactions (issues with blood flow).
  • Monoamine Oxidase-A Inhibitors (MAOIs): Taking MAOIs is suspected to increase the levels of some triptans by stopping the enzyme (monoamine oxidase) that breaks them down. This can create risks when also taking Imitrex. 
  • Other 5-HT1 Agonists: Due to the risk of prolonged vasospastic reactions (issues with blood flow), taking other drugs that affect 5-HT1 in the brain is not recommended.
  • Selective Serotonin Reuptake Inhibitors (SSRIs), Serotonin and Norepinephrine Reuptake Inhibitors (SNRIs), or Tricyclic Antidepressants (TCAs): Imitrex can affect serotonin levels in the brain and body. When combined with other serotonin-affecting medications, the risk for a potentially life-threatening condition called serotonin syndrome increases. Imitrex should not be taken while taking SSRIs, SNRIs, or TCAs. 

Always discuss current medications, vitamins, nutritional supplements, or herbal products you are taking with your doctor before starting a new medication.

What to avoid when taking Imitrex

  • Avoid using Imitrex more than 10 times each month. Overuse of Imitrex has the potential to increase the frequency of migraine headaches, and to make headaches worse.
  • The drug manufacturer recommends avoiding breastfeeding within 12 hours of taking Imitrex (sumatriptan). Research has found low levels of sumatriptan in breast milk after subcutaneous administration (injection) of the medication. Research is not yet complete on the oral administration of Imitrex and its effects on breast milk. 

Precautions Before Taking Imitrex

Imitrex can increase your risk for serious cardiovascular effects and changes such as myocardial infarction or stroke.

Warning signs of a cardiac event or stroke include:

  • Chest pain
  • Shortness of breath
  • Sudden irregular heartbeat
  • Sudden rise in blood pressure
  • Slurred speech
  • Weakness or numbness in face, arms, or legs

It’s not recommended that those with existing heart problems or heart disease take Imitrex or other triptans.

Some individuals taking Imitrex have had anaphylactic responses to taking the medication.

Signs and symptoms of anaphylaxis include low blood pressure, feeling lightheaded or faint, breathing difficulties, clammy or sweaty skin, hives, nausea, and vomiting.

Anaphylaxis can be fatal if not treated. 

Medications like Imitrex may cause a side effect called serotonin syndrome, especially if taken with other medications that impact serotonin, like SSRIs, SNRIs, TCAs, and MAOIs.

When too much serotonin builds up in the body, it can cause this syndrome, which can be life-threatening.

Symptoms of serotonin syndrome may include:

  • Agitation
  • Abnormally high body temperature
  • Nausea
  • Diarrhea
  • Muscle spasms
  • Rapid changes in blood pressure or heartbeat
  • Vomiting
  • Hallucinations

Taking Imitrex can sometimes cause dizziness or drowsiness, so plan your activities accordingly.

If you are taking Imitrex for the first time, don’t operate machinery or drive until you know how it affects you.

Risk factors

There are some risks when taking Imitrex (sumatriptan), including changes during pregnancy and the potential for medication overuse.

If you become pregnant while you are prescribed Imitrex, tell your doctor immediately.

You may need to switch medications or come up with an alternative migraine or headache care plan.

To study the effect of Imitrex on fetuses, there is currently a registry for those who are pregnant while taking the medication.

Doctors are encouraged to register their patients to this list with the company GlaxoSmithKline by calling 1-800-336-2176.

If you are planning on becoming pregnant, talk with your doctor before starting Imitrex, as there is some indication of fertility issues with prolonged use. 

There is a risk for medication overuse if you take Imitrex more than 10 times in a 30-day period.

Overuse of Imitrex can lead to worsened or more frequent migraine headaches.

If overuse persists, migraines may become a daily occurrence and require a detoxification program from the medication.

Imitrex Alternatives

Imitrex is not recommended for pediatric patients.

Caution should be used if this medication is used in patients over age 65.

Per the medication label, “dose selection for an elderly patient should be cautious, usually starting at the low end of the dosing range, reflecting the greater frequency of decreased hepatic, renal, or cardiac function and of concomitant disease or other drug therapy.”

Some alternative medications include Zomig (zolmitriptan) and Maxalt (rizatriptan).

  • Zomig: Like Imitrex, this is a triptan prescribed to be taken at the first sign of a migraine. It does not prevent or reduce the frequency of headaches or migraines.
  • Maxalt: Maxalt is another triptan. A comparative study found that patients reported faster relief of pain symptoms when taking Maxalt compared to those who took Zomig.

Other examples of selective serotonin receptor agonists that can be prescribed for headaches and migraines include triptans such as Axert (almotriptan), Frova (frovatriptan), and Amerge (naratriptan).

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When to See a Medical Provider

If you experience prolonged or worrisome side effects, talk to your doctor about whether your should continue with the medication.

If you experience any severe side effects or signs of overdose, serotonin syndrome, or cardiac events, call 9-1-1 for immediate emergency medical help.

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Frequently Asked Questions

What does Imitrex do to the body?
Imitrex acts on certain receptors in the brain to constrict blood vessels and prevent pain messages from being sent and received. This reduces your pain during a migraine or headache. The same function also reduces your sensitivity to light and sounds during migraines.
Is Imitrex a narcotic?
Imitrex is not a narcotic. Imitrex is classified as a selective serotonin receptor agonist. Narcotics are a class of drugs that are opioid-based, such as morphine. Imitrex is not addictive.
What are the side effects of Imitrex?
Side effects of Imitrex include, but aren’t limited to, flushing, tingling feelings, drowsiness, weakness, dizziness, upset stomach, nausea, and diarrhea.
When should I take Imitrex for migraines?
If you have a prescription, take an Imitrex dose when you feel your headache or migraine starting. Wait at least two hours before taking a second dose if the migraine persists.
K Health articles are all written and reviewed by MDs, PhDs, NPs, or PharmDs and are for informational purposes only. This information does not constitute and should not be relied on for professional medical advice. Always talk to your doctor about the risks and benefits of any treatment.

Jennifer Nadel, MD

Dr. Jennifer Nadel is a board certified emergency medicine physician and received her medical degree from the George Washington University School of Medicine. She has worked in varied practice environments, including academic urban level-one trauma centers, community hospital emergency departments, skilled nursing facilities, telemedicine, EMS medical control, and flight medicine.

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