# Scalp Cooling System

How a cold cap and chilled coolant loop help keep hair during chemotherapy, by narrowing scalp blood flow and slowing the hair roots\.

By Subrai Pai

Topic: Human Body & Medicine

[Open the interactive Jig](https://ask.jig.com/j/D9CE5r9PHXgH)

## Transcript

### 1. A cold cap that helps save hair

Some medicines that fight cancer can make hair fall out\. A scalp cooling system is a small fridge on wheels joined by two hoses to a snug cap\. By cooling the scalp, it helps many people keep more of their hair\.

Drag the scene to look around it\.

### 2. Why hair can fall out

Chemotherapy medicine travels in the blood and attacks cells that divide quickly, like cancer cells\. Hair roots, called follicles, also divide quickly, so the medicine reaches them too\. This magnified slice of scalp shows medicine \(purple dots\) flowing into the roots\.

### 3. Two layers on the head

Closest to the head sits a soft blue silicone cap full of narrow channels\. A grey neoprene cover goes on top to hold the cap tight and keep the cold in\. A snug fit matters, because air gaps stay warm\.

The cap comes in several sizes to fit different heads\.

### 4. Start the cold loop

The cooling unit chills a special liquid below freezing\. A pump sends it up one hose, through the channels of the cap, and back down the other hose to be chilled again\. The liquid never touches the skin\.

Blue pulses travel to the cap; paler pulses carry warmer liquid back\.

### 5. Cold calms the blood flow

A cold scalp makes its tiny blood vessels narrow, so less blood, and less medicine, reaches the hair roots\. The cold also slows the roots down, so they take in less\. Switch the cooling off and on to compare\.

### 6. Inside the cooling unit

Inside, a fridge system chills a tank of coolant, much like a kitchen freezer\. A pump keeps the liquid moving around the loop, and a screen lets the nurse set and watch the temperature\.

One common model holds about 8\.5 litres of coolant\.

### 7. Before, during and after

Cooling starts about 30 minutes before the medicine begins, so the scalp is already cold\. It carries on during the treatment and for up to about 90 minutes afterwards\. It is repeated at every treatment session\.

### 8. Good to know

It feels very cold at first, then most people get used to it, and a warm blanket helps\. It works best with some medicines and does not save every hair\. It is the cold, not the cap itself, that does the work\.

Not the same as a frozen gel cap, which must be swapped as it warms up\.