How to Switch from Aimovig to Nurtec (Rimegepant)

Aimovig (erenumab) and Nurtec (rimegepant) both target the CGRP pathway but work differently. Aimovig is a monoclonal antibody that blocks the CGRP receptor, administered as a monthly subcutaneous injection. Nurtec is a small molecule CGRP receptor antagonist (gepant) taken orally. Here's why patients commonly switch:

1. Prefer oral over injection: Aimovig requires monthly self-injections using an autoinjector pen. While the injection is relatively simple, many patients experience injection anxiety, injection site reactions (redness, swelling, pain in ~30% of patients), or simply prefer taking a pill. Nurtec is an oral dissolving tablet — place it on the tongue and it dissolves in seconds.

2. Want acute + preventive in one medication: Aimovig is preventive-only — it reduces migraine frequency but cannot treat an active attack. Patients on Aimovig still need a separate acute medication (triptan, gepant, or NSAID). Nurtec is unique: it's FDA-approved for both preventive (75mg every other day) and acute (75mg as needed) use. This means one medication can serve both roles.

3. Aimovig side effects: The most notable Aimovig side effect is constipation, reported in 3–4% of clinical trial participants but anecdotally more common in practice, with some patients experiencing severe constipation requiring treatment. Other Aimovig-specific concerns include muscle spasms, cramps, and rare reports of hypertension.

4. Inadequate response to Aimovig: If Aimovig hasn't provided sufficient migraine reduction after 3–6 months, switching to a different CGRP mechanism (gepant vs. mAb) can be effective. Patients who don't respond to one CGRP approach may respond to another.

5. Cost or insurance changes: Insurance formulary changes may make one medication more accessible than the other. Both manufacturers offer savings programs, but coverage varies.

The switch from Aimovig to Nurtec is straightforward because Aimovig's long half-life provides a natural bridge:

Aimovig pharmacokinetics:

• Half-life: approximately 28 days
• After your last injection, effective drug levels persist for 4–6 weeks
• Full washout takes approximately 5 half-lives (~140 days / 5 months), but clinically meaningful levels drop significantly after 6–8 weeks

Recommended transition approach:

• Month 1 (last Aimovig injection): Take your final Aimovig dose as scheduled. Begin Nurtec at the end of this month or the start of the next. There is no drug interaction between the two — they can overlap safely.
• Month 2 (start Nurtec): Begin Nurtec 75mg every other day for preventive use. Aimovig is still in your system, providing additional coverage during the transition. Use Nurtec 75mg as needed for any acute attacks.
• Month 3+: Aimovig levels are declining. Nurtec is now your primary preventive. Evaluate effectiveness at the 3-month mark.

What to expect during the overlap: Most patients experience a smooth transition because Aimovig provides background prevention while Nurtec builds its preventive effect. Some patients report a brief uptick in migraine frequency during weeks 6–10 as Aimovig wears off and before Nurtec's full preventive benefit is established. This is temporary.

No washout needed: There is no requirement to clear Aimovig from your system before starting Nurtec. In fact, the overlap period is beneficial — it prevents a gap in preventive coverage.

Nurtec (rimegepant 75mg) is uniquely versatile. Understanding how to use it correctly is key to getting the most from this switch:

For prevention:

• Take 75mg every other day (EOD) — e.g., Monday, Wednesday, Friday, Sunday, Tuesday, etc.
• Set an alternating-day alarm or use a pill organizer to stay on schedule
• Take it at any time of day, with or without food
• The ODT (orally dissolving tablet) goes on your tongue — no water needed
• Full preventive benefit develops over 4–8 weeks

For acute treatment:

• Take 75mg at migraine onset
• Do NOT take a second dose within 24 hours
• If you're already on the preventive schedule and get a migraine on an "off" day, take your Nurtec that day (effectively making it two consecutive days)
• Onset of pain relief: approximately 1–2 hours; pain freedom at 2 hours in ~21% (vs. 11% placebo)

Combining both uses:

• Many patients take Nurtec EOD for prevention and use it acutely on breakthrough days
• Your total monthly consumption should not exceed the prescribed amount — discuss with your provider
• Unlike triptans, Nurtec does not carry a significant medication overuse headache risk with frequent use

Compared to Aimovig dosing: Aimovig is a single monthly injection — simple but inflexible. Nurtec requires more frequent dosing (every other day) but provides both preventive and acute coverage. If you valued Aimovig's "set and forget" simplicity, the EOD schedule is a trade-off to consider.

Both medications are well-tolerated, but their side effect profiles differ in important ways:

Aimovig side effects you may leave behind:

• Constipation — The most notable Aimovig side effect. Erenumab blocks the CGRP receptor, and CGRP plays a role in gut motility. Some patients develop severe, treatment-resistant constipation requiring laxatives or even switching medications.
• Injection site reactions — Redness, swelling, itching, or pain at the injection site (~30% of patients)
• Muscle spasms/cramps — Reported by some patients, possibly related to CGRP's role in smooth muscle regulation
• Hypertension — Rare post-marketing reports of new or worsening high blood pressure; FDA added a warning in 2021

Nurtec side effects to expect:

• Nausea — 1.4–2.7% in clinical trials (mild, transient)
• Abdominal pain/dyspepsia — Uncommon but reported
• Hypersensitivity reactions — Rare; includes rash, dyspnea, facial swelling. Discontinue if severe.
• No constipation signal — Gepants don't cause the constipation seen with erenumab
• No injection site reactions — Obvious advantage of oral dosing

Liver considerations: Gepants are metabolized by the liver (CYP3A4 pathway). Rimegepant should be avoided with strong CYP3A4 inhibitors (ketoconazole, clarithromycin) and inducers (rifampin, carbamazepine). Periodic liver function testing may be recommended for patients on long-term preventive gepant therapy, though clinically significant hepatotoxicity has been very rare.

Overall: If constipation is your reason for leaving Aimovig, Nurtec should resolve this. If injection aversion is the driver, Nurtec's oral dissolving tablet is a welcome change. Most patients find Nurtec's side effect profile to be very mild.