Ajovy (Fremanezumab) Side Effects and Monitoring
Ajovy is generally well-tolerated with minimal monitoring requirements—the most common side effect is injection site reactions (erythema, pain, induration), and the primary safety concern is allergic reactions that can occur within hours to 1 month after injection. 1
Common Side Effects
Injection site reactions are the most frequently reported adverse events:
These reactions are typically mild to moderate and self-limiting. In pooled safety data from clinical trials, 48-69% of patients reported adverse events, with most being these injection site reactions 3.
Nasopharyngitis (common cold symptoms) was reported in 64% of patients in long-term studies 2, though this is likely coincidental rather than drug-related.
Serious Side Effects Requiring Immediate Action
Allergic reactions are the most important safety concern and require patient education 1:
- Can occur within hours to up to 1 month after receiving Ajovy
- Symptoms requiring emergency care:
- Swelling of face, mouth, tongue, or throat
- Trouble breathing
- Severe itching, rash, or hives
Instruct patients to call their healthcare provider or seek emergency care immediately if these symptoms develop.
Monitoring Requirements
Ajovy requires minimal routine monitoring compared to traditional migraine preventives 3:
No Routine Laboratory Monitoring Needed
- Unlike valproate (requires liver function and platelet monitoring) or topiramate (requires metabolic panels), fremanezumab does not require routine blood work
- Abnormal liver function tests occurred in only 1% of fremanezumab patients versus <1% with placebo 4
- Cardiovascular adverse events were uncommon and occurred at similar rates to placebo 3
Clinical Monitoring
Assess treatment response at 2-3 months after initiation:
- Reduction in monthly migraine days (primary efficacy measure)
- Reduction in headache days of at least moderate severity
- Reduction in acute medication use
- Improvement in disability scores (HIT-6)
Monitor for injection site reactions at each visit, particularly in the first few months.
Screen for allergic reactions at each follow-up, especially within the first month after each dose.
Special Populations
Pregnancy and Breastfeeding
- Safety in pregnancy is unknown 1
- A pregnancy registry exists (1-833-927-2605 or www.tevamigrainepregnancyregistry.com)
- Enroll patients who become pregnant during treatment
- Unknown if fremanezumab passes into breast milk 1
Pediatric Patients (Ages 6-17)
- Recently approved for episodic migraine in patients ≥45 kg 5, 6
- Injection-site erythema was the most common adverse event (9.8% vs 5.4% placebo) 5
- Safety profile similar to adults
Important Clinical Considerations
Immunogenicity
- Anti-drug antibody development is rare (2.4%) 2
- No routine antibody testing required
Discontinuation Rates
- Very low discontinuation rate (4% from adverse events, 2% from lack of efficacy) 2
- This is substantially better than traditional preventives like topiramate, which has high discontinuation rates due to adverse effects 7
Storage and Administration
- Store refrigerated at 36-46°F (2-8°C) 1
- May be kept at room temperature (up to 86°F) for maximum 7 days—discard if longer
- Do not freeze—discard if frozen
- Allow to sit at room temperature for 30 minutes before injection 1
Contraindications
The only absolute contraindication is hypersensitivity to fremanezumab-vfrm or any ingredient in Ajovy 1.
Notably, the 2021 guideline mentions fremanezumab is not recommended in patients with history of 8:
- Stroke or subarachnoid hemorrhage
- Coronary heart disease
- Inflammatory bowel disease
- Chronic obstructive pulmonary disease
- Impaired wound healing
However, this appears to be based on theoretical concerns rather than demonstrated harm in clinical trials.
Key Advantages Over Traditional Preventives
Fremanezumab has a superior safety profile compared to first-line agents 7:
- No need for dose titration
- No cognitive side effects (unlike topiramate)
- No weight gain (unlike amitriptyline, valproate)
- No cardiovascular monitoring (unlike beta-blockers)
- No teratogenicity concerns like valproate
- Minimal drug interactions
The excellent tolerability translates to sustained long-term use with maintained efficacy throughout 12 months 2, addressing the common problem of poor adherence with traditional preventives.