Flow’s real-world data shows less than 2% report minor side effects such as headaches and skin irritation.
A 2020 study found effects to be mild, transient and well-tolerated.
For the majority taking antidepressants, side effects are inevitable; a large international cohort showed that 61% of users reported at least 10 adverse effects, such as feeling emotionally numb (71%) and suicidality (50%).
FDA breakthrough device designation for at-home depression treatment
Approved by the British Standards Institution (BSI)
Class IIa medical device CE-marked. Approved for use in the EU and UK
Tested according to IEC 60601 for electrical medical device safety
Flow in the media
Over 12,000 people have used the Flow tDCS device. Less than 2% have reported side effects.
This list includes known side effects from the Flow tDCS device (until August 2023):
Headache (~1.5 %)
Skin irritation (~1.2%)
Mild skin burn (~0.5%)
Worsening of symptoms (~0.4%)
Increased anxiety (~0.3%)
Skin redness (~0.15%)
tDCS should NOT be used in the following cases:
The patient has a cranial or intracranial implant
The patient’s skull is not intact
The patient has a skin condition, for example psoriasis
The following conditions are not contraindications, but may require extra precautions – such as careful monitoring:
Bipolar disorder (or a history of hypomanic/manic episodes)
Epilepsy (or a history of seizures)
A recent surgical procedure
An active implanted medical, metallic or electronic device (such as a cardiac pacemaker, spinal cord stimulator, cochlear implant, implanted hearing aid or defibrillator)
There is no evidence to suggest that tDCS treatment could be harmful to use during pregnancy. The electric current targets the brain directly without affecting the hormonal or digestive systems, making tDCS a tempting option for treating depression during the peripartum period.
However, more large-scale controlled trials are needed before any definitive conclusions can be drawn.
Today, the option to use tDCS during the peripartum period should be carefully evaluated in each individual case.
Encouraging research results for tDCS during pregnancy:
2018 – Kurzeck et al: A systematic review concluding that the scientific evidence for tDCS during pregnancy is sparse but promising.
2019 – Vigod et al: A pilot randomised controlled trial showing promising results for tDCS during pregnancy. There were no serious adverse events.
2022 – Laurin et al: A systematic review including seven studies and 33 women. No serious adverse effects for the mothers or children.
Weeks 1-3: Includes 5 stimulation sessions a week, each 30 minutes long.
Weeks 4 and beyond: Includes 1-2 stimulation sessions a week, each 30 minutes long.
Patients usually see results within the first 3 weeks of treatment. The length of the treatment depends on depression severity and chronicity in each individual case. A recent RCT study showed that 57% of participants with moderate to severe depression reached remission within 10 weeks.
Clinicians can create custom schedules.
There is currently Level B evidence (probable effect) for the use of tDCS on several conditions. A few of these conditions are treated by targeting the same area as the Flow tDCS device – the left dorsolateral prefrontal cortex (DLPFC).
tDCS treatment usually targets the left DLPFC in:
Cognitive symptoms of Parkinson’s disease
Auditory hallucinations in Schizophrenia (however the cathode is placed differently – over the left temporoparietal area)
A minority of studies have used the left DLPFC as a target for the treatment of pain disorders.
tDCS treatment usually targets other brain areas in:
Alcohol addiction (usually the right DLPFC)
Epilepsy (cathode placed over the affected area)
Neuropathic pain (motor cortex)
Migraine (motor cortex)
Fibromyalgia (motor cortex)
Stroke rehabilitation (motor cortex)
Level C evidence
There is currently Level C evidence (possible effect) for the use of tDCS in:
Obsessive-Compulsive Disorder (targeting the pre−SMA)
Aphasia (various placements, some targeting Broca’s area)
There is promising and growing evidence for tDCS treatment of ADHD symptoms.
In 2022, a randomised, double-blind, controlled trial showed that at-home tDCS treatment significantly improved attention in 64 adult patients with ADHD. The treatment used the anode over the right DLPFC.
Clinical trials indicate that tDCS sessions can be used for at least 6 months without any changes in side effects, suggesting the treatment is suitable for long-term use.
There is no evidence to suggest that side effects would increase beyond 6 months, but few such long-term studies exist.
In comparison, most clinical studies on antidepressant medication follow up for a maximum of 5 months.
There is promising evidence indicating that tDCS can be used to prevent relapse.
See for example:
2019 – Aparicio et al: After the initial protocol of 15 tDCS sessions, participants were offered 2 weekly tDCS sessions for 6 months. The treatment was well tolerated with relatively low levels of relapse.
2013 – Valiengo et al: tDCS was effective both as a treatment in the acute phase of depression and as relapse prevention.
Our trial will be peer reviewed and published in Q1 2024. In the meantime, you can hear Daniel our Chief Clinical Officer talking about the methodology and results in a webinar, here.