Cefaly is a small wearable device that sticks to your forehead and sends mild electrical pulses through the skin to stimulate branches of the trigeminal nerve, the major nerve involved in migraine pain. By changing how that nerve sends signals to the brain, it can both prevent migraines and reduce pain during an active attack. It was the first device of its kind to receive FDA clearance for migraine treatment.
What the Device Does to Your Nerves
The trigeminal nerve is the largest nerve in your head. It has three main branches, and the one running across your forehead (the ophthalmic branch) plays a central role in migraine. Cefaly targets this branch by delivering tiny electrical impulses through a self-adhesive electrode placed just above the eyebrows. Those impulses travel through the skin and reach the nerve fibers underneath, altering the way they fire and communicate with the brain.
This process, called external trigeminal nerve stimulation, triggers a cascade of changes in your nervous system. The most important ones involve three areas: pain-signaling chemicals in the brain, the balance between excitatory and calming brain activity, and your body’s autonomic “background” systems like heart rate and inflammation.
How It Calms Migraine Signaling
During a migraine, nerve cells in the brain become hyperexcitable. They release too much glutamate, a chemical that ramps up neural activity. This creates a self-reinforcing loop: overactive receptors release more glutamate, which activates more receptors, which can fuel the spreading wave of abnormal electrical activity thought to underlie migraine aura and pain.
Trigeminal nerve stimulation interrupts this loop. It dials down the receptors that respond to glutamate while simultaneously boosting the activity of calming interneurons that release GABA, the brain’s main inhibitory chemical. The net effect is a quieter, less excitable brain, one that is less likely to tip into the runaway neural firing that produces a migraine. This rebalancing of excitatory and inhibitory signaling is a key reason the device works as a preventive treatment, not just a pain reliever.
Stimulation also influences the autonomic nervous system. It nudges your body toward a parasympathetic (“rest and digest”) state, which triggers the release of acetylcholine. In the spleen, acetylcholine acts on immune cells to reduce the production of inflammatory molecules, creating a mild anti-inflammatory effect throughout the body. Because neuroinflammation is a core feature of migraine, this systemic calming likely contributes to the device’s preventive benefit.
Two Modes for Two Purposes
Cefaly has two distinct settings that use different electrical frequencies to achieve different goals.
The preventive mode runs at 60 Hz (60 pulses per second) for a 20-minute session, once per day, every day. This lower-frequency stimulation is designed to gradually reduce the excitability of the trigeminal nerve over time, making your brain less prone to migraine triggers. Think of it as ongoing maintenance for your nervous system.
The acute mode runs at 100 Hz for a 60-minute session and is meant to be used at the onset of a migraine attack. The higher frequency provides faster, more intense nerve modulation aimed at stopping pain in progress. In a phase 3 clinical trial, 25.5% of patients using the real device were completely pain-free at two hours, compared to 18.3% using a sham (inactive) device. Both modes use the same pulse width of 250 microseconds.
What It Feels Like
When you turn Cefaly on, you feel a tingling or buzzing sensation across your forehead. The intensity ramps up gradually. Most people describe it as unusual but not painful. In a survey of over 2,300 users, only about 2% found the sensation uncomfortable enough to stop using the device. Sleepiness during a session is actually one of the more commonly reported experiences (about 0.5% of users), which some people consider a feature rather than a side effect.
The most frequently reported issues were discomfort from the tingling (2%), sleepiness or fatigue (0.8%), and headache after the session (0.5%). Skin irritation at the electrode site occurred in about 0.2% of users. No serious adverse events were reported. Overall, 4.3% of users experienced any side effect at all, placing it well below the side-effect burden of most migraine medications.
Who Should Not Use It
Cefaly is not appropriate for everyone. You cannot use it if you have a cardiac pacemaker, an implanted defibrillator, or any metallic or electronic implant in your head. The FDA clearance also specifies that it should not be used for chronic migraine, refractory migraine, medication overuse headache, or chronic tension-type headache. It is intended for episodic migraine specifically.
You should also avoid using the device in the bath or shower, while sleeping, while driving, or near electronic monitoring equipment like cardiac monitors. The electrode is designed only for the forehead and should never be placed on the neck or chest.
How It Compares to Medication
Cefaly does not replace medication for everyone, but it fills a specific niche. For people who cannot tolerate the side effects of preventive migraine drugs, or who prefer a drug-free approach, it offers a daily routine with a very low risk profile. It can also be used alongside medications without interactions, since it works through electrical nerve modulation rather than chemistry in the bloodstream.
The trade-off is that its acute pain-relief numbers are more modest than those of fast-acting migraine drugs. A 25.5% pain-freedom rate at two hours is meaningful but not as high as what some prescription options achieve. Where Cefaly tends to shine is in the cumulative, long-term reduction of migraine frequency through daily preventive use, particularly for people who want to reduce their reliance on medication over time.