Reviewed on 10/26/2022

What Is Fremanezumab and How Does It Work?

Fremanezumab is a prescription medication used for preventive treatment of migraine.

  • Fremanezumab is available under the following different brand names: Ajovy, fremanezumab-vfrm

What Are Side Effects Associated with Using Fremanezumab?

Common side effects of Fremanezumab include:

  • pain, redness, or a hard lump where the medicine was injected

Serious side effects of Fremanezumab include:

  • hives,
  • difficulty breathing,
  • swelling of the face, lips, tongue, or throat

Rare side effects of Fremanezumab include:

  • none 

Seek medical care or call 911 at once if you have the following serious side effects:

  • Severe headache, confusion, slurred speech, arm or leg weakness, trouble walking, loss of coordination, feeling unsteady, very stiff muscles, high fever, profuse sweating, or tremors;
  • Serious eye symptoms such as sudden vision loss, blurred vision, tunnel vision, eye pain or swelling, or seeing halos around lights;
  • Serious heart symptoms include fast, irregular, or pounding heartbeats; fluttering in the chest; shortness of breath; sudden dizziness, lightheadedness, or passing out.

This is not a complete list of side effects and other serious side effects or health problems that may occur because of the use of this drug. Call your doctor for medical advice about serious side effects or adverse reactions. You may report side effects or health problems to FDA at 1-800-FDA-1088.

What Are the Dosages of Fremanezumab?

Adult dosage

Injectable solution

  • 225 mg/1.5 mL (single-dose prefilled syringe or autoinjector)

Migraine Prophylaxis

Adult dosage

  • 225 mg Subcutaneous once monthly
  • Alternatively, 675 mg every 3 months (quarterly), administered as 3 consecutive 225-mg subcutaneous doses
  • When switching dosage options, administer the first dose of the new regimen on the next scheduled date of administration

Dosage Considerations – Should be Given as Follows: 

  • See “Dosages”


Who suffers more frequently from migraine headaches? See Answer

What Other Drugs Interact with Fremanezumab?

If your medical doctor is using this medicine to treat your pain, your doctor or pharmacist may already be aware of any possible drug interactions and may be monitoring you for them. Do not start, stop, or change the dosage of any medicine before checking with your doctor, health care provider, or pharmacist first.

  • Fremanezumab has no noted severe interactions with any other drugs.
  • Fremanezumab has no noted serious interactions with any other drugs.
  • Fremanezumab has no noted moderate interactions with any other drugs.
  • Fremanezumab has no noted minor interactions with any other drugs.

This information does not contain all possible interactions or adverse effects. Visit the RxList Drug Interaction Checker for any drug interactions. Therefore, before using this product, tell your doctor or pharmacist about all your products. Keep a list of all your medications with you and share this information with your doctor and pharmacist. Check with your healthcare professional or doctor for additional medical advice, or if you have health questions or concerns.

What Are Warnings and Precautions for Fremanezumab?


  • History of serious hypersensitivity reactions to drugs or excipients

Effects of drug abuse

  • None

Short-Term Effects

  • See “What Are Side Effects Associated with Using Fremanezumab?”

Long-Term Effects

  • See “What Are Side Effects Associated with Using Fremanezumab?”


  • Use caution in patients with cardiovascular disease; not studied
  • Hypersensitivity reactions
    • Cases of anaphylaxis, angioedema, rash, pruritus, drug hypersensitivity, and urticaria reported within hours to 1 month following administration in clinical trials
    • Some reactions led to discontinuation or required corticosteroid treatment
    • Consider discontinuing therapy, and institute appropriate therapy if a hypersensitivity reaction occurs

Pregnancy and Lactation

  • There is a pregnancy exposure registry that monitors pregnancy outcomes in women exposed to the drug during pregnancy; healthcare providers are encouraged to register pregnant patients, or pregnant women may enroll themselves in the registry by calling 1-833-927-2605 or visiting
  • There are no adequate data on the developmental risk associated with therapy in pregnant women; the drug has a long half-life, which should be taken into consideration for women who are pregnant or plan to become pregnant while receiving therapy
  • Clinical considerations
    • Published data have suggested that women with migraine may be at increased risk of preeclampsia and gestational hypertension during pregnancy
    • Lactation
    • There are no data on the presence of human milk, its effects on the breastfed infant, or milk production
    • Consider the developmental and health benefits of breastfeeding along with the mother’s clinical need for the drug, and any potential adverse effects on the breastfed infant from the drug or the underlying maternal condition

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