Tailbone pain is one spot. It sits on the midline, at the very base of the spine, lower than most people expect. People describe it as worst when they lean back in a chair and at the moment they stand up.
It is a different problem from sit-bone pain, which is two spots, one on each side. The difference matters, because the two want opposite shapes of seat.
Why sitting loads the tailbone
Sit upright and your weight goes through the two sit bones. The tailbone, the last few small bones of the spine, sits just behind and above them and carries very little.
Lean back or slump, and the pelvis rolls backward. The load moves off the sit bones and onto the back of the pelvis and the tailbone. On a hard seat, or a soft one that lets you sink until the tailbone finds the surface, that one small point ends up carrying weight it was not built to carry.
What usually sets it off
Clinicians list a few common causes of a sore tailbone: a fall onto it, childbirth, and long hours sitting on hard or narrow seats. Often no single cause is found. A seat can change only one thing on that list: what the tailbone rests on while you sit.
Tailbone or sit bones? Check before you buy anything
- One spot on the midline, at the base of the spine: the tailbone.
- Two spots, left and right, where you would land on a wooden bench: the sit bones.
Slumping back usually makes a tailbone worse and eases the sit bones; sitting upright does the reverse. The full comparison has the details, including what to do when both hurt. If the spot is somewhere else again, this map of where sitting hurts sorts it out.
What changes the mechanics
Sit on your sit bones, not behind them
Sitting upright, or leaning slightly forward, moves the load to the two bones built for it. A chair back that supports the lower spine makes that easier to hold than willpower does.
Get up before it builds
A minute on your feet every half hour takes the load off entirely, and costs nothing.
Take the seat away from that one point
A coccyx cushion has a U-shaped cutout at the rear edge. Sit back against the chair and the tailbone hangs over open space while the sit bones and thighs carry the weight on firm foam. How the U-shaped cutout works, and why the foam has to be firm enough not to let you sink back onto the seat.
A ring-shaped donut takes away the middle instead, which suits a different spot: donut cushions compared with cutouts.
Tailbone-first
The U-cutout coccyx cushion — the tailbone touches nothing. 14,000+ Amazon ratings.
When to see a doctor
A cushion changes what you sit on. It does not treat anything. See a clinician about tailbone pain that follows a fall and is not settling, that comes with numbness, weakness or trouble with your bladder or bowels, that comes with a fever or a lump, or that is still there after a few weeks of sitting differently.
The short version
- Tailbone pain is one midline spot; sit-bone pain is two.
- Leaning back rolls weight onto the tailbone; sitting upright moves it to the sit bones.
- A rear U-shaped cutout leaves the tailbone over open space.
- It is the opposite shape from a sit-bone cushion, so find the spot first.