At-Home tDCS for Depression: The Flow Neuroscience FL-100 Headset

What Is the Flow Neuroscience Device?

The Flow Neuroscience device is the FL-100, a wearable tDCS headset that delivers 2.0 mA of constant direct current to the dorsolateral prefrontal cortex through saline-soaked electrodes for 30-minute sessions, paired with a companion behavioral therapy app. The system is prescription-only in the United States and is manufactured by Flow Neuroscience AB, a Swedish medical device company founded in 2016.

The FL-100 has 3 components working as one prescription system:

Every FL-100 ships with a starter pack of replacement electrode sponges. Sponges are saline-soaked before each session and replaced approximately every 30 sessions.

FDA Status and Clinical Efficacy

The FL-100 holds FDA premarket approval P230024 issued December 8, 2025, the first PMA granted for an at-home tDCS device in the United States. The device is classified as Class III under product code JXK (cranial electrotherapy stimulator) and is indicated as monotherapy or as an adjunct to antidepressant medication for moderate-to-severe major depressive disorder in adults 18 and older. Prior medication failure is not required by the label.

Clinical efficacy rests on 4 evidence streams:

1. The Empower pivotal trial. The 174-participant sham-controlled randomized trial demonstrated a statistically significant reduction in Hamilton Depression Rating Scale scores at 10 weeks versus sham stimulation, with 45–58% response rates and remission rates in the same range across active arms (Flow Neuroscience pivotal data submitted under PMA P230024).
2. Real-world EU data. The Flow device has been distributed to more than 55,000 users in the European Union since 2019, including supervised use within the United Kingdom National Health Service (NHS), with manufacturer-published outcomes showing 77% of users report symptom improvement after 3 weeks of daily use.
3. Independent meta-analyses. Cochrane reviews and 2020–2025 meta-analyses on tDCS for major depressive disorder report a small-to-moderate effect size, with strongest results when tDCS is combined with antidepressants or psychotherapy.
4. Safety profile. Adverse events reported in registration trials are mild and transient, with a self-reported side-effect rate of 4.5%, dominated by skin tingling, mild headache, and transient redness at electrode sites.

The device received FDA Breakthrough Device designation in 2022 and CE Mark Class IIa approval in the United Kingdom and the European Union prior to US approval.

Full details and official labeling available in the FDA Summary of Safety and Effectiveness (P230024).

The Science of Neuromodulation and tDCS

Transcranial direct-current stimulation (tDCS) is a non-invasive neuromodulation technique that delivers a low-intensity constant electrical current (typically 1–2 mA) through scalp electrodes to modulate the resting membrane potential of underlying cortical neurons. The current does not fire neurons directly. It shifts the probability that targeted neurons will fire when the brain is active, which over repeated sessions produces durable changes in cortical excitability and circuit-level connectivity.

For major depressive disorder, the standard depression montage places the anode over the left dorsolateral prefrontal cortex (DLPFC) at the F3 site of the international 10–20 EEG system and the cathode over the right supraorbital region or the right DLPFC. Anodal stimulation increases excitability of the left DLPFC, a region consistently shown to be hypoactive in patients with major depressive disorder on functional imaging. The mechanism is hypothesized to restore prefrontal-limbic regulatory balance through cumulative long-term potentiation, with effects that build over a multi-week course rather than a single session.

Neuromodulation is the broader category. It covers transcranial direct-current stimulation, transcranial magnetic stimulation (TMS), cranial electrotherapy stimulation (CES), vagus nerve stimulation, and deep brain stimulation. The FL-100 is the first at-home consumer-grade neuromodulation device approved by the FDA for a primary psychiatric indication.

Safety and At-Home Self-Administration

The FL-100 has three built-in safeguards that make at-home tDCS safe:

1) The device itself automatically limits the current to a safe level by capping stimulation at 2.0 mA

2) The headset’s fixed electrode geometry keeps the electrodes in the right position every session

3) A real-time impedance check refuses to start a session if scalp contact is poor

The entire system is engineered so the patient doesn’t need to adjust or calibrate anything — it stays safely within the correct ranges automatically. Additional safety comes from the required clinical evaluation and prescription process before use.

The current generator caps stimulation at 2.0 mA. The headset’s fixed electrode positions prevent montage drift. The impedance check refuses to start a session if scalp contact is poor. The companion app blocks session start outside the prescribed schedule. Layered on top of the hardware are the clinical screen at intake, the weekly clinician monitoring during the acute phase, and adjustment or cessation if someone reports worsening symptoms or skin reactions.

Is tDCS Safe for Home Use?

At-home tDCS is safe when delivered through an FDA-approved device under clinical supervision, with a self-reported side-effect rate of 4.5% in Flow Neuroscience real-world data and no serious adverse events causally linked to the FL-100 in registration trials. Safety conclusions apply to prescribed, on-label use of the FL-100 specifically. Off-label do-it-yourself tDCS rigs and unapproved consumer headsets do not share this safety profile and are not equivalent.

Common, transient side effects include skin tingling at electrode sites, mild headache lasting under 1 hour, and brief redness that resolves within 30 minutes of session end. Contraindications absolute or relative cover 6 categories:

• Implanted electrical devices. Pacemakers, deep brain stimulators, cochlear implants, vagus nerve stimulators.
• History of seizure or epilepsy. Personal or first-degree family history.
• Skin conditions at electrode sites. Active eczema, open lesions, recent forehead surgery.
• Pregnancy. Insufficient pregnancy safety data; case-by-case clinician decision.
• Active substance use. Acute intoxication or withdrawal increases seizure risk.
• Severe psychiatric instability. Active psychosis, severe mania, or acute suicidality requiring higher level of care.

Stop the session and contact your clinician within 24 hours for any of 5 red-flag symptoms: persistent headache lasting more than 4 hours, scalp burn or blistering, new or worsening suicidal thoughts, a new seizure, or any new neurological symptom such as numbness or weakness.

How to Position and Use the Headset

The FL-100 headset is positioned and used in 6 sequential steps following the F3-anode depression montage, with each session running 30 minutes at 2.0 mA inside the Flow companion app. The headset’s fixed geometry does most of the placement work. Your job is skin prep, sponge saturation, fit check, and adherence.

Run the session in this order:

1. Prepare the skin. Wash your forehead with a mild, fragrance-free cleanser and dry it fully. Skip moisturizer, makeup, and sunscreen on the forehead before a session.
2. Soak the sponges. Saturate both sponge electrodes in the supplied saline solution for 30–60 seconds. Squeeze out excess so sponges are wet but not dripping.
3. Seat the headset. Position the crown so the front sponge sits centered above the left eyebrow and roughly 7 cm forward of midline (the F3 site over the left dorsolateral prefrontal cortex). The cathode sponge sits over the right supraorbital region. The fixed geometry keeps the montage correct.
4. Run the impedance check. Open the Flow app, start the session, and wait for the impedance check to clear. If impedance is high, re-wet the sponges and reseat the headset.
5. Run the 30-minute session. Sit or lie down during the session. The current ramps up gradually, holds at 2.0 mA for the treatment period, and ramps down at the end. Mild tingling at session start is expected and fades within 1–2 minutes.
6. Log and store. Log mood and any side effects in the app at session end. Rinse sponges with distilled water, air dry, and store the headset on the supplied stand.

Each starter pack of electrode sponges supports approximately 30 sessions. Replacement pads are shipped on a recurring schedule synced to your prescribed protocol.