Indications
Prescription antiemetics are often considered the treatment of choice in an emergency setting because they are fast acting and relatively safe. Sometimes, antiemetics are used alone or along with other medications for treatment of status migrainosus, which is a severe migraine lasting for at least 72 hours despite treatment.
Children may receive antiemetics for migraine treatment because nausea and vomiting can be the predominant or only identifiable feature of childhood migraines.
Unlike opiods, antiemetics are not addictive, so they are also an option for people who could be at risk of opioid-induced side effects or addiction.
Antiemetics are generally considered the safest migraine medication for pregnant people and their growing babies. Some data suggest that the antiemetic metoclopramide is the most commonly prescribed migraine medication for pregnant people in hospital care.
Over-the-Counter
Several over-the-counter (OTC) medications including Dramamine (dimenhydrinate), Bonine (meclizine), and Benadryl (diphenhydramine), which are often used for motion sickness, can help reduce migraine-associated nausea.
These medications are available in oral form. OTC antiemetics take effect more slowly than the prescription strength options, so they are generally not useful for the treatment of emergency situations such as status migrainosus. Nevertheless, they have almost no side effects and some migraineurs experience improvement of migraine attacks.
How They Help Migraines
Over-the-counter antiemetics do not work in the same way as prescription-strength antiemetics. For example, dimenhydrinate is an antihistamine that reduces nausea by speeding up gastrointestinal movement. Meclizine is an anticholinergic medication that decreases the brain’s sensitivity to movement, reducing symptoms of motion sickness.
Prescription antiemetics have a different effect on the body than other migraine treatments and a very different type of action than over-the-counter options. They are dopamine antagonists, which means that they block the receptors that allow dopamine, a neurotransmitter, to function.
Dopamine normally fine-tunes muscle movements, and it also modifies mood and pain. Many dopamine antagonist antiemetics are actually antipsychotics, because excess dopamine action is linked with hallucinations, psychosis, and conditions such as schizophrenia. These medications reduce nausea and vomiting through their dopamine antagonist action in the brain and the gastrointestinal (GI) system.
Antiemetics are not always effective for treating migraines, however, and they can induce distressing short-term and long-term side effects, which include involuntary muscle movements.
Compazine (prochlorperazine)
Compazine (prochlorperazine) is commonly used to treat nausea, and it can be used to treat acute migraine attacks, with or without nausea.
Compazine exerts its antiemetic effects by acting centrally (in the brain) and can be used in the treatment of schizophrenia and the short-term treatment of generalized non-psychotic anxiety. It is also an antihistamine (like Benadryl) and can help reduce vascular headaches.
Compazine is available in tablet form, sustained-released capsules, an oral liquid form, suppository, and can be given intravenously (IV through the vein) or intramuscularly (IM into the muscle). Taken orally, effects begin between 30 and 40 minutes. Taken intramuscularly, effects start between 10 and 20 minutes. For both routes of administration, effects generally last for up to four hours.
Potential side effects include drowsiness, dizziness, blurry vision, skin reaction, low blood pressure, and amenorrhea (slowing or absence of menstrual periods). Muscle movements described as “extrapyramidal effects” may also occur, including muscle spasms, restlessness, Parkinsonism, or tardive dyskinesia. A rare but potentially life-threatening reaction called neuroleptic malignant syndrome (NMS) causes fever, muscle rigidity, and confusion.
Thorazine (chlorpromazine)
Thorazine (chlorpromazine) is an antipsychotic that blocks excess dopamine from accumulating in the brain. While Compazine is used more often for migraines, Thorazine is typically prescribed to treat psychosis. However, it is sometimes used to treat severe nausea and vomiting as well.
Thorazine can be given orally, intramuscularly, or intravenously for migraine and nausea relief. It is also available as a suppository. When taken orally via tablet or an extended-release formulation, effects set in between 30 and 60 minutes and can last upwards of 12 hours. When taken rectally, the effects of chlorpromazine diminish after four hours.
Potential side effects include drowsiness, dizziness, weight gain, vertigo, dry mouth, blurred vision, and sexual dysfunction. An estimated 1 in 500 people who take chlorpromazine develop a type of acute liver injury known as cholestasis, which can result in jaundice, nausea, and itchy skin. In most cases, cholestasis is not severe, but it should be treated promptly.
Reglan (metoclopramide)
Reglan (metoclopramide) blocks dopamine receptors in the gastrointestinal system. It can help empty your stomach by increasing gastrointestinal motility (movement).
Reglan is commonly used to treat migraine-related nausea and vomiting, especially in the emergency room or urgent care setting. It comes in oral, intravenous, and intramuscular formulations. Oral formulations should be taken 30 minutes before a meal, and effects tend to set in between 30 and 60 minutes. Intravenous metoclopramide can provide relief in as fast as 1 to 3 minutes. For both routes of administration, effects generally last for up to two hours.
While Reglan tends to have fewer side effects than other antiemetics, common side effects include restlessness, fatigue, dizziness, headaches, confusion, problems sleeping, depression, and suicidal thoughts. Like other dopamine antagonists, serious side effects like extrapyramidal symptoms and NMS can occur but are very rare.
A Word From Verywell
Antiemetics can be very effective treatments for acute migraine attacks. They are not preventive, and prescription antiemetics are not usually recommended to be taken on a regular basis as a migraine treatment.
If nausea is a major part of your migraines, it is worthwhile to try to figure out whether you experience migraines during your prodromal (pre-headache) phase, during the migraine itself, or your postdromal (post-migraine) phase. This can help you and your healthcare provider as you create a treatment plan.
