Imitrex (sumatriptan) is a prescription brand-name medication. It’s approved by the Food and Drug Administration (FDA) to treat migraine, with or without aura, in adults. In addition, the injection form of Imitrex is approved to treat cluster headaches in adults.

Here are some fast facts about Imitrex:

  • Active ingredient: sumatriptan
  • Drug class: serotonin receptor agonists (commonly known as triptans)
  • Drug forms: oral tablet, nasal spray, single-dose vial and syringe,* Imitrex STATdose pen*

If Imitrex works for you, your doctor may have you use it long term, but only when needed.

Like other drugs, Imitrex can cause side effects. Read on to learn about potential common, mild, and serious side effects. For a general overview of Imitrex, including details about its forms and uses, see this article.

* The injection forms of Imitrex are given as subcutaneous injections.

Imitrex can cause certain adverse effects (side effects). Some of Imitrex’s side effects are more common than others. Common side effects may vary by which form of the drug you use to treat your condition. To learn more about your risks of these effects with certain forms of Imitrex, talk with your doctor or pharmacist.

In clinical trials of Imitrex tablets, some commonly reported side effects included:

  • tingling, numbness, or prickling feelings, usually in the arms, hands, feet, or legs
  • pain, tightness, or heaviness in the chest
  • dizzy spells
  • general discomfort or fatigue
  • odd hot or cold feelings

In clinical trials of Imitrex nasal spray, some commonly reported side effects included:

  • irritation or burning sensation in the nose, throat, or both
  • nausea* or vomiting
  • a bad or strange taste in the mouth
  • dizzy spells

In clinical trials of Imitrex injections, some commonly reported side effects included:

  • reactions at the injection site, such as redness or discoloration, pain, swelling, or burning sensation
  • tingling, numbness, or prickling feelings
  • odd hot or cold feelings
  • dizzy spells

* To learn more, see the “Side effect specifics” section below.

Mild side effects can occur with Imitrex use. This list doesn’t include all possible mild side effects of the drug. For more information, refer to Imitrex’s prescribing information for the form of the drug you’re using: tablet, nasal spray, or injection.

Mild side effects reported with all forms of Imitrex included:

  • dizzy spells
  • odd hot or cold feelings
  • pain, tightness, or heaviness in your chest, throat, neck, or jaw

Mild side effects reported with Imitrex tablets included:

  • tingling, numbness, or prickling feelings, usually in the arms, hands, feet, or legs
  • general discomfort or fatigue

Mild side effects reported with Imitrex nasal spray included:

  • irritation or burning sensation in the nose, throat, or both
  • a bad or strange taste in the mouth
  • vomiting
  • nausea*

Mild side effects reported with Imitrex injections included:

  • weakness, general discomfort, or fatigue
  • tingling, numbness, or prickling feelings, usually in the arms, hands, feet, or legs
  • reactions at the injection site, such as redness or discoloration, pain, swelling, or burning sensation
  • drowsiness*

Often, these side effects are temporary or easily managed. However, if any side effects persist, bother you, or become severe, be sure to talk with your doctor or pharmacist.

Note: After the Food and Drug Administration (FDA) approves a drug, it tracks side effects of the medication. If you develop a side effect while using Imitrex and want to tell the FDA about it, visit MedWatch.

* To learn more, see the “Side effect specifics” section below.

Imitrex may cause serious side effects. The list below may not include all possible serious side effects of the drug. For more information, refer to Imitrex’s prescribing information for the form of the drug you’re using: tablet, nasal spray, or injection.

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

The serious side effects below did not occur during clinical trials of Imitrex tablets, nasal spray, or injections. They either occurred after Imitrex came on the market, or they’re side effects of drugs called triptans. (Imitrex is a type of triptan.) The side effects and their symptoms include:

  • Cardiovascular problems, such as heart attack or unstable angina (type of chest pain). Symptoms can include:
    • nausea or vomiting
    • pain, tightness, or heaviness in your chest, throat, neck, or jaw
    • shortness of breath, with or without chest pain
  • Cerebrovascular problems (disorders related to the brain and its blood vessels), such as stroke. Symptoms can include:
    • slurred or difficult speech
    • severe, sudden headache
    • facial numbness or weakness
  • Arrythmia (irregular heart rate or rhythm). Symptoms can include:
    • dizzy spells or fainting
    • fast, fluttering, or skipped heartbeats
    • pounding in your chest
  • Other blood vessel or blood flow disorders, such as Raynaud’s syndrome or decreased blood flow to your digestive tract. Symptoms can include:
    • nausea
    • bloody diarrhea
    • odd hot or cold feelings
    • purple or reddened skin tone
  • Seizures. Symptoms can include:
    • slurred or difficult speech
    • jerking or uncontrolled body movements
    • loss of consciousness
  • Severe hypertension (very high blood pressure). Symptoms can include:
    • extreme headache
    • dizzy spells or fainting
    • chest pain
  • Headache from using too much Imitrex.*
  • Allergic reaction.*

* To learn more, see the “Side effect specifics” section below.

Long-term side effects

Typically, migraine and cluster headaches are chronic, recurring conditions. If Imitrex works for you, your doctor may have you use it long term, but only when needed. You may experience certain side effects each time you use the medication.

Some side effects of Imitrex could be serious. Their symptoms could persist long after you’ve stopped your treatment. For example, if you have a heart attack or stroke with Imitrex, you may have lasting effects. These can include heart failure and paralysis (inability to move a body part).

If you’re concerned about serious, lasting side effects with Imitrex, talk with your doctor. They can advise you on whether the drug is right for you.

Imitrex may cause several side effects. Here are answers to some frequently asked questions about the drug’s side effects.

How do Imitrex side effects from the oral pill, nasal spray, and injection forms compare?

In general, the oral pill (tablet), nasal spray, and injection forms of Imitrex have similar mild and serious side effects.

However, some side effects are unique to the form of Imitrex you use for your condition. Here are some examples:

  • With Imitrex injections, you may have reactions where the shot is given. These can include redness or discoloration, pain, swelling, or burning sensation.
  • With the Imitrex nasal spray, you may notice bad or strange tastes in your mouth. Or you may feel nose or throat irritation.

Some common side effects may also differ by the drug’s form. For example, general discomfort and fatigue were commonly reported in clinical trials of Imitrex tablets. However, these side effects weren’t commonly reported in clinical trials of the nasal spray or injection forms.

For more information about common, mild, and serious side effects of Imitrex and how they vary by form, see those sections above in this article. You can also talk with your doctor or pharmacist.

Are weight loss and weight gain side effects of Imitrex?

No. Weight loss and weight gain aren’t reported side effects of Imitrex.

However, weight loss could be a symptom of decreased blood flow to your digestive tract. This is a rare but serious side effect of the drug. See your doctor right away if you have unexplained weight loss while using Imitrex.

If you’re concerned about weight changes while using Imitrex, talk with your doctor. They may be able to suggest ways to help you maintain a moderate weight.

What side effects are specific to the 50-mg and 100-mg doses of Imitrex?

Overall, the side effects seen with 50-milligram (mg) and 100-mg doses of Imitrex tablets are similar to those of the 25-mg dose. (The injection and nasal spray forms of the drug don’t come in these doses.)

The recommended starting dose of Imitrex tablets for treating migraine, with or without aura, is 25 mg, 50 mg, or 100 mg. You’ll take this dose when you start to have symptoms. Some people may feel more relief with the 50-mg or 100-mg doses than with the 25-mg dose. However, clinical trials show that a first dose of 100 mg may not work better than a 50-mg dose. The higher dose may also increase the risk of side effects.

For more information about side effects of Imitrex tablets, see the above sections. You can talk with your doctor about which dose of Imitrex tablets is right for you.

Does Imitrex cause stomach pain?

Abdominal pain (commonly referred to as stomach pain) wasn’t reported in clinical trials of Imitrex tablets, nasal spray, or injections.

However, abdominal pain can be a symptom of decreased blood flow to your digestive tract. This is a rare but serious side effect of Imitrex.

Abdominal pain can also be a symptom of migraine, which Imitrex is used to treat.

While using Imitrex, talk with your doctor right away if you have pain in your abdomen. They can help determine the cause and recommend treatment.

Is serotonin syndrome a side effect of Imitrex?

Serotonin syndrome wasn’t reported in clinical trials of Imitrex tablets, nasal spray, or injections. It’s a side effect of drugs called triptans. And Imitrex is a type of triptan.

Serotonin is a chemical in your brain and nervous system. It’s a “feel good” substance that you need for good mental health and other body processes. However, too much serotonin flooding your body at once can cause negative effects. These can include confusion, loss of consciousness, high heart rate, and hallucinations (seeing things that aren’t there). Other effects include high body temperature, nausea, vomiting, and diarrhea. A high level of serotonin is called serotonin syndrome.

Your risk of serotonin syndrome with Imitrex is highest if you use the drug while taking other medications that can increase serotonin levels. Examples of these drugs include:

You’re also more likely to develop serotonin syndrome shortly after using a new or higher dose of Imitrex.

Before you start using Imitrex, talk with your doctor if you’re taking an SSRI or a drug that can raise serotonin levels. They will likely prescribe the smallest Imitrex dose possible. During your Imitrex treatment, get medical help right away if you notice any symptoms of serotonin syndrome.

If you’re concerned about serotonin syndrome, talk with your doctor about migraine or cluster headache treatments that don’t affect serotonin levels. For example, newer migraine drugs called gepants don’t impact serotonin.

Learn more about some of the side effects that Imitrex may cause.

Headache from using too much Imitrex

Using Imitrex too often may cause a medication overuse headache (rebound headache). With this side effect, migraine may occur more often, you may develop more cluster headaches, or you may feel migraine-like pain every day.

Medication overuse headache is a common problem when using too much of certain drugs used to treat migraine, such as triptans. (Imitrex is a type of triptan.) However, this kind of headache usually occurs if you take these medications 10 or more days per month.

Symptoms of medication overuse headache can include pain that doesn’t allow you to function as usual, memory problems, and trouble sleeping.

What you can do

To help prevent an overuse headache with Imitrex, use it exactly as your doctor prescribes. They’ll likely suggest you treat only four headaches a month with the medication.

If you need to take medication 10 or more days per month to treat your condition, talk with your doctor. They may prescribe medication to help prevent migraine or cluster headaches. With preventive treatment, you may have fewer headaches and then use less Imitrex.

If you have headaches from using too much Imitrex, your doctor may also suggest that you don’t take migraine drugs for a time. During this period, you may still experience headaches while your body gets used to not having migraine medication. Ask your doctor how to manage these effects with nondrug treatments.

Nausea

The use of Imitrex may cause nausea. In clinical trials of the nasal spray form of the drug, nausea was a common side effect.

Nausea may also be a symptom of a serious side effect of Imitrex tablets, nasal spray, or injections. These side effects include:

In addition, many people feel nauseous or vomit during migraine. (Imitrex is used to treat migraine in adults.)

What you can do

If you have mild nausea with Imitrex nasal spray, talk with your doctor about using Imitrex tablets or injections instead. These forms may be less likely to cause this side effect.

You should also talk with your doctor if you usually feel nauseous during migraine. They may prescribe certain antiemetic medications, such as Phenergan (promethazine). Antiemetic medications help ease nausea and vomiting. You can also ask about non-drug treatments, such as herbal tea or breathing techniques.

If you have severe nausea or nausea with other symptoms that concern you while using Imitrex, see your doctor right away. If your symptoms feel life threatening, immediately call 911 or your local emergency number.

Drowsiness

Drowsiness may occur during treatment with Imitrex. This side effect was reported by people in clinical trials of Imitrex injections, but it wasn’t common.

Drowsiness wasn’t seen in clinical trials of Imitrex tablets or nasal spray. However, fatigue was common with the tablets.

Also, some people feel tired when they experience migraine or cluster headaches.

What you can do

Before driving or working with machines, see how Imitrex affects you. If you have drowsiness from the drug, be sure to rest until you’re more alert. Lying down may help ease migraine and headache symptoms, too.

You can also try to avoid other drugs that may make you sleepy, such as Benadryl (diphenhydramine) or other antihistamines. Be sure to talk with your doctor or pharmacist before taking any medication with Imitrex.

If you feel overly drowsy with Imitrex, talk with your doctor. They may suggest a different medication for your condition.

Allergic reaction

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

Symptoms can be mild or serious and can include:

  • skin rash
  • itching
  • flushing
  • swelling under your skin, typically in your lips, eyelids, feet, or hands
  • swelling of your mouth, tongue, or throat, which can make it hard to breathe

What you can do

For mild symptoms of an allergic reaction, call your doctor right away. They may recommend ways to ease your symptoms and decide whether you should keep using Imitrex. However, if your symptoms are serious and you think you’re having a medical emergency, immediately call 911 or your local emergency number.

Be sure to talk with your doctor about your health history before you use Imitrex. This drug may not be the right treatment for you if you have certain medical conditions or factors that affect your health. The conditions and factors to consider include:

Epilepsy or seizure risks. Imitrex may cause seizures. Your risk may increase if you have epilepsy or risk factors for seizures, such as a brain or head injury. Be sure to tell your doctor if you have or had seizures. You should also tell them about all medications you take because some may increase your risk of seizures.

Depending on your health and other factors, your doctor may prescribe Imitrex and monitor you closely during your treatment. Or, they may not prescribe Imitrex because of seizure risks and recommend a different medication.

Heart and blood vessel problems. Rarely, Imitrex may cause serious and, in certain cases, fatal problems related to your heart and its blood vessels. You may have an increased risk if you have a history of heart disease or risk factors for it. These factors include obesity, diabetes, and a strong family history of heart disease.

Tell your doctor about any risk factors and whether you or anyone in your family has heart problems. If you have risk factors for heart disease, they may order certain tests and watch you closely during your Imitrex treatment. If you have heart disease, it’s highly unlikely your doctor will prescribe Imitrex. They can advise you on a different treatment.

Disorders related to the brain and its blood vessels. Rarely, Imitrex may cause serious and, in certain cases, fatal problems related to your brain and its blood vessels. An example is stroke. It’s highly unlikely your doctor will prescribe Imitrex if you have a history of stroke or ministroke. They can suggest a different treatment for you.

Arrythmias. Imitrex may cause serious and, in rare cases, fatal arrythmias. Tell your doctor about any current or past arrhythmias. It’s highly unlikely they’ll prescribe Imitrex if you have a history of certain irregular heart rates or rhythms. They can recommend a different treatment for you.

Hypertension that’s not well managed. Imitrex may lead to episodes of hypertension that can cause organ damage. Your doctor will check your blood pressure before prescribing the medication. It’s highly unlikely they’ll prescribe Imitrex if your blood pressure isn’t well managed. Talk with your doctor about how to manage your blood pressure and the best way to treat your condition.

Severe liver disease. Be sure to talk with your doctor about your liver health. It’s unlikely that they’ll prescribe Imitrex if you have severe liver disease. If your liver isn’t healthy enough to break down the medication, the drug could build up in your body. Ask your doctor what other treatments may be safer for you.

Allergic reaction or allergies. If you’ve had an allergic reaction to Imitrex or any of its ingredients, it’s highly unlikely your doctor will prescribe Imitrex.

Also, you should talk with your doctor if you have serious allergies, such as severe seasonal allergies or allergies to eggs, bee stings, or peanuts. Your risk of an allergic reaction with Imitrex may increase if you’re highly sensitive to common allergens such as these.

In addition, before using the prefilled syringe form of Imitrex, tell your doctor if you have a latex allergy. The needle shield contains a type of rubber that could cause an allergic reaction if you’re allergic to latex.

Ask your doctor what other medications may be better for you.

Alcohol use with Imitrex

Alcohol doesn’t affect how Imitrex works in your body, but it’s best to avoid alcohol during your treatment.

Drinking alcohol may trigger migraine or cluster headaches in some people. And consuming alcohol while treating your condition with Imitrex may:

  • worsen your symptoms
  • worsen the drug’s side effects, such as drowsiness, nausea, vomiting, and dizzy spells

If you have questions about drinking alcohol and using Imitrex, talk with your doctor.

Pregnancy and breastfeeding while using Imitrex

Here’s some information about pregnancy, breastfeeding, and Imitrex.

Imitrex and pregnancy. The safety of Imitrex during pregnancy is unknown. Negative effects occurred in the fetuses of pregnant animals given sumatriptan during animal trials.* (Sumatriptan is the active ingredient in Imitrex.) However, outcomes in animals may not predict outcomes in humans.

Before using Imitrex during pregnancy, talk with your doctor. They can suggest the safest way to manage your condition.

Imitrex and breastfeeding. The safety of Imitrex use while breastfeeding is unknown. Sumatriptan passes into breast milk. However, it’s unclear if this affects milk production or a child who is breastfed.

Before using Imitrex while breastfeeding, talk with your doctor. They may suggest that you avoid breastfeeding for 12 hours after each Imitrex dose.

* For more information, refer to the prescribing information for Imitrex’s forms: tablet, nasal spray, or injection.

If you use Imitrex to treat migraine or cluster headaches, you may have side effects. They may vary by the form of the drug you use for your condition. In general, the common side effects of each form are mild and manageable. However, some of Imitrex’s side effects can be serious, so be sure to talk with your doctor if you develop any.

If you’d like to learn more about Imitrex, talk with your doctor or pharmacist. They can help address any concerns you have about side effects from using the drug. For example, if you think that Imitrex makes you “feel weird,” they can suggest ways to manage your symptoms.

Besides talking with your doctor, you can do some research on your own. These articles might help:

Disclaimer: Medical News Today 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.