If you have migraine, your doctor may prescribe Imitrex for you. Imitrex is a prescription medication that’s used to treat migraine headaches (with or without aura) in adults. The injectable form of Imitrex can also be used to treat cluster headaches in adults.

Imitrex is used on an as-needed basis. You’ll use it only when you have a headache.

Imitrex comes as tablet, nasal spray, or liquid solution. The solution is available in a vial (given by injection with a syringe) or in a prefilled cartridge (given by injection with the Imitrex STATdose pen).

For more information about Imitrex, including details about its uses, see this in-depth article. Like other drugs, Imitrex can cause mild or serious side effects. Keep reading to learn more.

Imitrex can cause certain side effects, some of which are more common than others.

Examples of Imitrex’s commonly reported side effects include:

  • dizziness
  • fatigue (low energy)
  • feeling unusually warm or cold
  • tingling or numbness in your fingers or toes*
  • pain, pressure, or tightness in your chest, throat, neck, or jaw
  • injection site reactions* (when using the injectable form of Imitrex)

* To learn more about this side effect, see “Side effects explained” below.

Mild side effects can occur in some people using Imitrex. Mild side effects that have been reported with this drug include:

  • dizziness
  • fatigue (low energy)
  • feeling unusually warm or cold
  • tingling or numbness in your fingers or toes*
  • pain, pressure, or tightness in your chest, throat, neck, or jaw
  • injection site reactions* (when using the injectable form of Imitrex)


In most cases, these side effects should be temporary. And some may be easily managed, too. But if you have any symptoms that are ongoing or that bother you, talk with your doctor or pharmacist. You shouldn’t stop using Imitrex unless your doctor recommends it.

Imitrex may cause mild side effects other than the ones listed above. For details, see the Imitrex patient information for the tablet, injection, and nasal spray.

Note: After the Food and Drug Administration (FDA) approves a drug, it tracks and reviews side effects of the medication. If you’d like to notify the FDA about a side effect you’ve had with Imitrex, visit MedWatch.

* To learn more about this side effect, see “Side effects explained” below.

Imitrex may cause serious side effects in some people. Serious side effects that have been reported with Imitrex include:

If you develop serious side effects during your Imitrex treatment, call your doctor right away. If the side effects seem life threatening or if you think you’re having a medical emergency, immediately call 911 or your local emergency number.

* To learn more about this side effect, see “Side effects explained” below.
† An allergic reaction is possible after using Imitrex. But it’s not clear whether this side effect occurred in studies.

Below are some frequently asked questions about Imitrex’s side effects.

How long do Imitrex side effects last, and does the drug cause any long-term side effects?

How long side effects from Imitrex last can vary. Some may be temporary, lasting from a few days to a few weeks. For example, injection-site reactions typically are gone within a day or two.

But more serious side effects, such as heart problems and stroke, may cause long-term complications.

If you have questions about how long certain side effects of Imitrex could last, talk with your doctor or pharmacist.

Can Imitrex cause weight loss?

Weight loss isn’t a direct side effect of Imitrex. But if you have unexplained weight loss during your treatment, it may be a sign of reduced blood flow to your stomach or intestines. This is a serious side effect of Imitrex.

If you experience unexplained weight loss while using Imitrex, tell your doctor right away.

Will the side effects of Imitrex vary depending on whether I take it as an oral pill, nasal spray, or injection?

Yes. Some side effects occur only with a certain form of Imitrex. For example, injection-site reactions only occur with the injectable form of the drug.

If using the nasal spray, your nose and throat may become irritated. The nasal spray could also cause a bad taste in your mouth. These side effects wouldn’t occur with the pill (tablet) form or the injection.

Will taking the 100-mg Imitrex pill increase my risk of side effects compared with the 50-mg and 25-mg pills?

Yes, it’s possible that a higher dose of Imitrex could raise your risk of side effects. Your doctor will likely prescribe you the lowest dose that’s effective for your condition. This may help reduce your risk of side effects.

Is joint pain a possible side effect of Imitrex?

No, joint pain wasn’t a side effect seen in studies of Imitrex.

Another medication used to treat migraine, Frova (frovatriptan), may cause joint pain. Frovatriptan is similar to sumatriptan (the active drug in Imitrex). But this side effect hasn’t been reported with sumatriptan.

If you experience joint pain during your Imitrex treatment, talk with your doctor.

See below to learn more about some of the side effects Imitrex may cause.

Injection-related side effects

Some people may receive Imitrex as an injection under the skin. When the drug is given this way, it’s possible to have a mild reaction in the area of the injection. Injection site reactions were a common side effect of the Imitrex injection in studies.

Injection site reactions may include:

  • pain
  • swelling of the skin
  • redness or discoloration
  • stinging or burning
  • bruising or bleeding

What might help

Injection site reactions are typically mild and may last only a day or two. If you have reactions that are bothersome or that last longer, talk with your doctor or pharmacist. They may be able to recommend ways to ease the side effect.

Tingling or numbness in your fingers or toes

Some people may experience tingling or numbness in their fingers and toes while using Imitrex. This happens when your blood doesn’t circulate as well as it should. In studies, tingling or numbness in the fingers or toes wasn’t common in people using Imitrex.

Symptoms may vary but can include:

  • numb fingers and toes
  • pain in your fingers or toes when they get cold

What might help

The symptoms listed above typically get worse if your fingers and toes become cold. Wearing socks and gloves may help lessen these symptoms. If your symptoms are bothersome or don’t go away, talk with your doctor or pharmacist. They may be able to recommend ways to ease the side effect.

Heart problems

Some people may experience heart problems while taking Imitrex. Heart problems that were reported in studies of Imitrex included heart attack, Prinzmetal’s angina, and irregular heartbeat.

Symptoms of heart problems may include:

  • severe pain, pressure, or tightness in your chest
  • shortness of breath
  • fast heart rate
  • feeling your heart skipping a beat
  • dizziness

What might help

Call your doctor or go to the emergency room right away if you experience any symptoms of heart problems.

If you’re concerned about your risk for heart problems with Imitrex, talk with your doctor before starting treatment. They can determine if this drug is right for you.

Stroke or bleeding in the brain

Using Imitrex may cause stroke or bleeding in the brain. These side effects have happened in people using medications similar to Imitrex, but they weren’t reported in studies of Imitrex.

Symptoms of a stroke or bleeding in the brain may include:

  • drooping on one side of the face
  • slurred speech or trouble speaking
  • sudden weakness or numbness on one side of the body
  • severe headache that happens suddenly

What might help

A stroke is a medical emergency. If you experience any of the symptoms above, call 911 or your local emergency number right away.

If you’re concerned about your risk for stroke or bleeding in the brain while using Imitrex, talk with your doctor or pharmacist before starting treatment.

Allergic reaction

Like most drugs, Imitrex can cause an allergic reaction in some people.

Symptoms can be mild or serious and can include:

  • skin rash
  • itchiness
  • flushing (temporary warmth, redness, or deepening of skin color)
  • swelling under your skin, typically in your eyelids, lips, hands, or feet
  • swelling of your mouth, tongue, or throat, which can make it hard to breathe

What might help

If you have mild symptoms of an allergic reaction, such as a mild rash, call your doctor right away. They may suggest an over-the-counter oral antihistamine, such as Benadryl (diphenhydramine), or a topical product, such as hydrocortisone cream, to manage your symptoms.

If your doctor confirms you had a mild allergic reaction to Imitrex, they’ll decide if you should continue using it.

If you have symptoms of a severe allergic reaction, such as swelling or trouble breathing, call 911 or your local emergency number right away. These symptoms could be life threatening and require immediate medical care.

If your doctor confirms you had a serious allergic reaction to Imitrex, they may have you switch to a different treatment.

Keeping track of side effects

During your Imitrex treatment, consider keeping notes on any side effects you’re having. Then, you can share this information with your doctor. This is especially helpful to do when you first start taking new drugs or using a combination of treatments.

Your side effect notes can include things such as:

  • what dose of drug you were taking when you had the side effect
  • how soon after starting that dose you had the side effect
  • what your symptoms were from the side effect
  • how it affected your daily activities
  • what other medications you were also taking
  • any other information you feel is important

Keeping notes and sharing them with your doctor will help your doctor learn more about how Imitrex affects you. And your doctor can use this information to adjust your treatment plan if needed.

Imitrex may not be right for you if you have certain medical conditions or other factors that affect your health. Talk with your doctor about your health history before you take Imitrex. The list below includes factors to consider.

Stroke or ministroke. If you’ve ever had a stroke or a ministroke, you should not use Imitrex. This drug can raise your risk for having a stroke, and your risk may be higher if you’ve had a stroke before. Talk with your doctor about other treatment options that may be safer for you.

Hemiplegic or basilar migraine. If you have hemiplegic migraine or basilar migraine, you shouldn’t use Imitrex. This is because both Imitrex and these types of migraine can raise your risk of having a stroke. Ask your doctor about other treatment options that may be safer for you. And if you’re not sure which type of migraine you have, talk with your doctor.

Peripheral vascular disease. You shouldn’t use Imitrex if you have peripheral vascular disease (PVD). PVD causes blood vessels in your arms, legs, stomach, or kidneys to narrow. Imitrex works by narrowing your blood vessels, so it could worsen your PVD. If you have PVD, talk with your doctor to see if other migraine or cluster headache treatment options may be better for you.

Heart disease. You shouldn’t use Imitrex if you have coronary heart disease or coronary artery vasospasm (including heart attack and angina), or if you’ve had these conditions in the past. Imitrex can raise your risk for heart problems, and this risk may be higher if you already have heart disease. Talk with your doctor about other treatment options that may be safer for you.

Risk factors for heart disease. In rare cases, Imitrex can cause a heart attack. Your risk of heart attack may be higher if you have certain risk factors for heart disease. Risk factors include older age, high cholesterol, high blood pressure, obesity, diabetes, smoking, or a family history of heart disease. If you have several of these risk factors, your doctor will check your heart health to determine whether Imitrex is safe for you.

Irregular heartbeat. You shouldn’t take Imitrex if you have an irregular heartbeat, including Wolff-Parkinson-White syndrome. Talk with your doctor about other treatment options for your condition.

High blood pressure. If you have high blood pressure that’s not well managed, you shouldn’t take Imitrex. This drug can raise your blood pressure, which can increase your risk of a heart attack or stroke. If you already have high blood pressure, talk with your doctor about other treatments that may be safer for you.

Ischemic bowel disease. You shouldn’t take Imitrex if you have ischemic bowel disease. With this condition, you have reduced blood flow to your bowels. Imitrex works by narrowing your blood vessels, so it may make your condition worse. Talk with your doctor about other treatment options that may be safer for you.

Seizures. Imitrex may cause seizures. If you have seizures or have had them in the past, you could have a higher risk for seizures with Imitrex. Talk with your doctor about whether Imitrex is right for you.

Liver problems. If you have liver problems, be sure to tell your doctor before using Imitrex. Having liver problems can affect how your body breaks down Imitrex, especially the tablet form. Your doctor may choose to prescribe the injection or nasal spray instead of the tablets if you have liver problems. Or they may prescribe a lower dose of Imitrex tablets. If your liver problems are severe, your doctor will recommend a medication other than Imitrex for you. This is because the drug hasn’t been studied in this population.

Allergic reaction. If you’ve had an allergic reaction to Imitrex or any of its ingredients, you shouldn’t use Imitrex. Ask your doctor what other medications may be better options for you.

Alcohol use and Imitrex

It should be safe to drink alcohol during your Imitrex treatment. But alcohol can trigger headaches in some people. If that’s the case for you, avoiding alcohol or limiting how much you drink may help prevent headaches.

If you drink alcohol, talk with your doctor about how much may be safe to drink while using Imitrex.

Pregnancy and breastfeeding while using Imitrex

It isn’t known whether Imitrex is safe to use during pregnancy. If you’re pregnant or planning to become pregnant, talk with your doctor about whether Imitrex is right for you.

It’s also unknown whether Imitrex is safe to use while breastfeeding. The injectable form of Imitrex can pass into breastmilk, but it’s not known whether this could cause side effects in a breastfed child.

If you’re breastfeeding or planning to breastfeed, talk with your doctor before using Imitrex.

Side effects can occur while using Imitrex, but they’re usually mild. Most mild side effects of the drug are temporary and don’t require medical attention.

If you’d like to learn more about Imitrex and its possible side effects, talk with your doctor or pharmacist. Examples of questions you may want to ask include:

  • Based on my health history, do I have a higher risk of side effects with Imitrex than other people?
  • How can I manage side effects from Imitrex?
  • What could happen if I become pregnant during my Imitrex treatment?

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Disclaimer: Healthline has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or another healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.