Article

Hyperbolic Tapering: Why "Linear" Cuts Fail at Low Doses

Research published in The Lancet Psychiatry by Dr. Mark Horowitz and Professor David Taylor has changed how we understand antidepressant withdrawal. The key finding: the relationship between dose and brain effect is not linear—it is hyperbolic.

The Receptor Occupancy Curve

Antidepressants (like SSRIs) work by inhibiting the serotonin transporter (SERT). Imaging studies show that this inhibition follows a hyperbolic curve:

• High Doses: At high doses (e.g., 20mg vs 40mg of citalopram), the difference in receptor occupancy is small. A large cut in milligrams has a small effect on the brain.
• Low Doses: At low doses (e.g., 2mg vs 0mg), the curve is steep. A tiny cut in milligrams causes a huge drop in receptor occupancy.

Why Linear Tapers Cause Withdrawal

Traditional guidelines often suggest linear reductions (e.g., 20mg → 15mg → 10mg → 5mg → 0mg).

The drop from 5mg to 0mg is often the hardest because it might represent a drop in receptor occupancy from ~20% to 0%, a massive shock to the system. This explains why many patients feel fine at first but "hit a wall" at lower doses.

The Solution: Proportional Reductions

To keep the biological effect on the brain consistent, dose reductions should be proportional (e.g., reducing by 10% of the current dose, not the original dose).

This leads to a "hyperbolic" taper where the milligram cuts get smaller and smaller as you get lower (e.g., 20mg → 10mg → 5mg → 2.5mg → 1.25mg...).

GentleStep and Hyperbolic Tapering

GentleStep is designed with this principle in mind. Our calculator supports percentage-based reductions, helping you visualize and plan these smaller, precise steps at the end of a taper where they matter most.

External Resources

Tapering of SSRI treatment to mitigate withdrawal symptoms (The Lancet Psychiatry, 2019)

Disclaimer: GentleStep is a tracking tool. We do not provide medical advice. Always consult your doctor before making changes to your medication.