What Are Flow-Through Booster Sheets? Uses, Precautions, and Product Examples [2026 Guide]

English translation of an article originally published in Japanese on June 11, 2019. Read the Japanese original (Japanese). Product information and dates refer to the original article. Images and manufacturer videos may contain Japanese.

Caution

Flow-through absorbent sheets should not be chosen casually. They are considered when extra absorbency is needed or when a thin person’s body shape causes persistent leakage.

About flow-through absorbent sheets

Diagram of urine passing through a flow-through sheet with no waterproof backing

Unlike ordinary urinary incontinence pads, flow-through absorbent sheets have no waterproof backing. Absorbed urine can therefore pass through to the pad underneath. They are used to supplement absorbency or fill gaps caused by a thin build.

How to use flow-through absorbent sheets

Using them for additional absorbency

Flow-through sheet layered inside tape-fastened adult diapers and pull-on adult diapers

To supplement absorbency, combine them with tape-fastened adult diapers or pull-on adult diapers. Some size S diapers have lower absorbency, so they can be useful in these situations.

Hiroshi Yagi

Outside Japan, these are called booster pads. Their role is to provide additional absorbency.

Thicker tape-fastened adult diapers and pull-on adult diapers side by side

Some diapers in size M or larger provide sufficient absorbency without adding a flow-through sheet.

Placing them in gaps caused by a thin build

Flow-through sheet placed in the gap between tape-fastened adult diapers and the body

When a person is thin, the pad may not fit closely to the body, leaving gaps that cause leakage. A flow-through sheet can be used as an aid in these gaps.

Flow-through absorbent sheet precautions

Combining them with urinary incontinence pads

Layers of tape-fastened adult diapers, a men's pad, and a flow-through sheet

Urinary incontinence pads come in many sizes and absorbencies. Before adding a flow-through sheet, check whether an appropriate urinary incontinence pad can meet the need. Unnecessary layering adds bulk and may restrict movement.

Review the diaper size first

Comparison of leg gaps with different diaper sizes

An incorrectly sized tape-fastened adult diaper or pull-on adult diaper may leave gaps. If the size is too large, consider a smaller size.

Hiroshi Yagi

Flow-through sheets are recommended for thin people whose leakage through gaps persists even after moving to a smaller diaper size.

Use in special fitting methods

Comparison of male wrapping and accordion folding with a flow-through sheet

Diaper manufacturers sometimes introduce male wrapping and accordion folding as ways to use flow-through sheets.

Caution

Adult Diaper Information Center Japan does not recommend using flow-through sheets for male wrapping or accordion folding.

Male wrapping

Wrapping a urinary incontinence pad around the penis may leave much of its absorbent surface unused. A flow-through sheet provides a wider absorbing area.

Male incontinence pads: types, wrapping methods and precautions [2026]

Accordion folding

Accordion folding is a special fitting method sometimes introduced for women. It may restrict movement.

Why these methods are not recommended

Male wrapping and accordion folding often involve a urinary incontinence pad layered inside tape-fastened adult diapers. Layering increases bulk and may restrict movement.

Changing a male-wrapped flow-through sheet together with the pad underneath

Male wrapping and accordion folding are used to prevent urine soiling from spreading to the buttocks or to reduce the work involved in changes.

Urine spreading from a flow-through sheet to the pad underneath, requiring both to be changed

With a flow-through sheet, urine also spreads to the pad underneath, so it does not eliminate pad changes. If used for male wrapping or accordion folding, combine it only with tape-fastened adult diapers.