Aimovig Side Effects and Your Legal Rights

Aimovig and Its Potential Risks

Aimovig® (erenumab) represents a breakthrough in migraine prevention as the first FDA-approved medication that specifically targets brain pathways involved in migraine pain. While many patients have found relief from debilitating migraines with this treatment, concerning reports have emerged about serious Aimovig side effects that weren’t fully disclosed to patients. These include severe constipation leading to hospitalization and surgery, high blood pressure, hair loss, and other complications that have significantly affected patients’ lives.

As lawyers specializing in dangerous prescription drug cases, particularly those involving inadequately warned serious side effects, we’re investigating potential claims related to Aimovig complications.

What Is Aimovig and How Does It Work?

Aimovig (erenumab) is a specialized medication that blocks specific pain pathways in the brain linked to migraines. It was the pioneer in a new class of migraine preventive medications, receiving FDA approval in May 2018 as the first treatment specifically designed to block these migraine pain pathways. Two similar medications, Ajovy and Emgality, were approved later in 2018, and all three are administered by injection under the skin once a month for migraine prevention.

Aimovig works slightly differently from its competitors: it blocks the receptor (or docking station) for a pain-signaling substance in the brain, whereas Ajovy and Emgality bind to the pain substance itself.

The medication is given as a once-monthly injection under the skin using either a prefilled syringe or autoinjector. The recommended dose is 70 mg, though some patients may benefit from a higher 140 mg dose. In clinical trials, Aimovig helped reduce the number of monthly migraine days compared to placebo (dummy treatment).

The History of Aimovig and FDA Approval

Developed by Amgen and Novartis, Aimovig received FDA approval on May 17, 2018, marking a significant milestone as the first treatment specifically targeting migraine pain pathways. Before approval, the drug underwent several clinical trials to test its safety and effectiveness.

In these clinical trials, Aimovig’s side effect rates appeared low and similar to placebo for most events. The most common side effects reported in these controlled studies (occurring in 2% or more of patients and more often than with placebo) were injection site reactions and constipation. Specifically, injection site reactions occurred in about 5-6% of Aimovig-treated patients versus 3% on placebo, and constipation in 1-3% of patients (versus 1% on placebo).

However, as with many medications, a more complete picture of Aimovig’s safety has emerged as more patients used it in real-world settings, revealing side effects not initially reported in the more controlled environment of clinical trials.

Side Effects and Complications

Common Aimovig Side Effects

The more common side effects of Aimovig include:

• Injection site reactions: Pain, redness, and swelling where the injection was given are among the most frequently reported side effects. These reactions were seen in about 5-6% of patients receiving the 70 mg dose and were slightly more common in those receiving the 140 mg dose. Most injection site reactions go away within a few days.
• Mild constipation: Initially reported in a small percentage of patients in clinical trials but has become more prominently recognized after the drug came to market.
• Muscle cramps and spasms: Reported in less than 1% of patients receiving the 70 mg dose and in about 2% of those receiving the 140 mg dose.
• Other common reactions: Include headache (4.5%), cold or flu-like symptoms (4.5%), nausea, and tiredness.

Serious Aimovig Side Effects and Complications

Severe Constipation

Perhaps the most alarming development has been the reports of severe constipation associated with Aimovig. Digestive system side effects, especially constipation, have emerged as a major issue. While only about 1-3% of patients reported constipation in clinical trials, real-world data show a much higher occurrence. Constipation has become the single most frequently reported side effect for Aimovig in the FDA’s side effect tracking system.

One analysis found that Aimovig had a ten-fold higher reporting of constipation compared to other similar migraine medications. Many Aimovig users have experienced severe constipation, sometimes requiring medical intervention.

Within two years of launch, enough cases of serious constipation had accumulated that Amgen updated Aimovig’s prescribing information to add a warning about “constipation with serious complications.” There have been reports of constipation severe enough to cause bowel blockage, hospitalization, and even requiring surgery.

After Aimovig became widely prescribed, constipation quickly emerged as the most frequently reported adverse event in the FDA’s side effect reporting system. By the end of its first year on the market, over 1,000 constipation cases had been logged, including hundreds considered serious—some involving emergency room visits, surgical procedures, or hospitalization for bowel blockages.

In many of these severe cases, the constipation occurred after the first dose or early in treatment, and most patients improved after stopping Aimovig. Real-world clinical studies support this concern: one headache center reported that 42-43% of their Aimovig-treated patients experienced constipation, with around 12% of patients stopping Aimovig due to severe side effects (including stubborn constipation).

Constipation is much less common with the other similar migraine drugs. Only about 3% of reported side effects for Ajovy or Emgality included constipation.

High Blood Pressure and Heart Effects

After Aimovig came to market, reports showed that it can cause increases in blood pressure in certain patients. High blood pressure was not a significant finding in the controlled trials (rates were less than 1% and similar to placebo). However, soon after Aimovig’s approval, scattered reports emerged of new high blood pressure or blood pressure spikes in patients starting the drug.

An FDA analysis documented 61 cases of elevated blood pressure with Aimovig, including 41 serious cases and 7 that required hospitalization. By April 2020, the FDA and manufacturers had enough evidence to update Aimovig’s label, adding a warning about development of high blood pressure (or worsening of existing high blood pressure) during therapy.

Many of the reported high blood pressure cases occurred shortly after the first dose (within the first week), and some patients had no prior history of high blood pressure. Some cases required blood pressure medication or hospitalization. In most cases, the blood pressure returned to normal after Aimovig was stopped.

Serious heart and blood vessel problems have also been reported rarely with this class of drugs, though it’s difficult to determine whether Aimovig directly caused these problems. In reports to the FDA, there were isolated cases of heart attack, chest pain, stroke, and a rare brain blood vessel condition in patients receiving Aimovig.

Hair Loss After Using Aimovig

An unexpected side effect that emerged after Aimovig came to market is hair loss. Dozens of patients on Aimovig began reporting hair loss – something not seen in clinical trials – through patient forums and FDA reports. By mid-2022, over 1,100 cases of hair loss associated with Aimovig had been reported to the FDA.

This was roughly double the number reported for Emgality (approximately 554 cases) and many times more than for Ajovy (approximately 175 cases) in the same timeframe. A medical review published in 2023 concluded that hair loss is an “emerging side effect” with these migraine medications, especially Aimovig.

Most reported cases were in women. In the documented cases, hair loss typically began within weeks to a few months of starting therapy. Some patients reported that switching to a different similar migraine drug did not fully prevent the problem.

The suspected cause is that blocking these pain pathways may affect blood flow to hair follicles or trigger stress responses in hair follicles, leading to temporary hair thinning. As of 2025, hair loss is now listed in the postmarketing section of the official prescribing information of Aimovig.

Allergic Drug Reactions

Like other similar medications, Aimovig can cause allergic reactions. A few serious allergic reactions have occurred, including severe allergic reactions with swelling and difficulty breathing. Most allergic reactions happened within hours of an injection (occasionally days later) and were managed by stopping the drug and standard treatment for allergies.

In 2020, the FDA updated Aimovig’s label to include a warning against use in patients with serious allergic reactions to Aimovig or any of its ingredients. Most allergic reactions were not serious and occurred within hours of injection, although some occurred more than one week after injection.

Symptoms of serious allergic reactions may include swelling of the face, mouth, tongue, or throat; trouble breathing; rash; and hives. If a serious allergic reaction occurs, stopping Aimovig and getting medical treatment is recommended.

Other Reported Aimovig Side Effects

Through FDA side effect reporting, several other issues have been identified as potentially linked to Aimovig. By the end of 2020 (about 2 years after launch), over 23,000 Aimovig side effect reports had already been submitted to the FDA. An independent analysis of those reports found that the majority (about 84%) were classified as non-serious, and about 65% involved female patients. Still, 146 fatal cases were recorded in that period.

Other potential side effects that may be linked to Aimovig include:

• depression
• anxiety
• insomnia
• weight changes
• rapid heartbeat
• blood clots in the lungs
• heart attacks, and
• flu-like illness

These were reported more often than expected compared to other migraine medications.

A large-scale safety study likewise found new side effects occurring with all these migraine drugs that were not in the original trial data or package inserts. For example, poor circulation in fingers and toes causing them to turn white or blue (Raynaud’s phenomenon), weight gain, menstrual changes, throat tightness, and numbness in the mouth were flagged as side effects appearing across multiple similar migraine drugs.

Aimovig Label Updates and FDA Warnings

Since its approval in 2018, Aimovig’s FDA label has been updated several times to reflect emerging safety information. In 2020, the FDA added a safety-related change to warn against use in patients with serious allergic reactions to Aimovig or its ingredients. This update was based on reports of allergic reactions after the drug came to market.

Warnings regarding severe constipation complications and high blood pressure have also been added to the product labeling. These warnings advise healthcare providers to monitor patients for these potential side effects and provide guidance on when to seek medical attention.

These label updates reflect the FDA’s ongoing monitoring of Aimovig’s safety and commitment to providing healthcare providers and patients with the most current safety information. However, for many patients who experienced serious side effects, these warnings may have come too late.

Understanding Your Legal Rights as a Patient

When you’re prescribed a medication like Aimovig, you have the right to be fully informed about its potential risks and side effects so you can make an educated decision about your treatment. Drug companies have a legal obligation to adequately test their products for safety before marketing them and to provide clear warnings about known risks.

If you’ve suffered serious complications from Aimovig that weren’t adequately warned about when you began treatment, you may have grounds for legal action. These cases generally fall under product liability law, which holds manufacturers responsible for placing unreasonably dangerous products on the market or failing to warn about known risks.

Pharmaceutical companies can potentially be held liable for:

1. Failure to warn about known or reasonably foreseeable risks
2. Defective design of the medication
3. Manufacturing defects that affect the safety of the drug
4. Improper marketing that downplays risks or exaggerates benefits

If you’ve suffered complications such as severe constipation requiring hospitalization or surgery, new high blood pressure leading to medical intervention, significant hair loss, or other serious side effects from Aimovig, you may be entitled to compensation for:

• Medical expenses (past and future)
• Lost wages and reduced ability to earn
• Pain and suffering
• Emotional distress
• Other damages related to your injuries

How an Experienced Drug Injury Lawyer Can Help

Taking on a case against a drug company can be challenging. These corporations have vast resources and teams of lawyers dedicated to defending against liability claims. Having an experienced dangerous drug attorney on your side can level the playing field.

Our legal team can help you by:

1. Investigating your case: Reviewing your medical records and the timing of your Aimovig use in relation to your complications.
2. Consulting with medical experts: Working with specialists who can establish the connection between your injuries and Aimovig.
3. Determining liability: Identifying all potentially responsible parties, which may include the drug manufacturer, marketers, or even prescribing physicians in some cases.
4. Navigating complex legal procedures: Managing deadlines, paperwork, and legal requirements that are critical to preserving your right to compensation.
5. Negotiating on your behalf: Using our experience with similar cases to pursue a fair settlement that adequately compensates you for all your damages.
6. Representing you at trial if necessary: Presenting your case effectively if a fair settlement cannot be reached.

Contact us About Your Rights

Have you experienced severe constipation, high blood pressure, hair loss, or other serious side effects requiring hospital care after taking Aimovig? Contact our legal team for a free consultation.

We have over 27 years experience holding corporations accountable and we work on contingency fee basis, meaning you pay nothing unless we win compensation for you.

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