I pulled my pillowcase off to wash it and the pillow underneath was yellow. Not a little yellow — like someone had spilled tea on it and let it dry. I considered throwing the pillow away. Then I looked up what causes pillow yellowing and realized it is not dirt. It is sweat, saliva, and skin oils that seep through the pillowcase over months of sleeping. Everyone’s pillows do this. You are not gross. Your pillow is just absorbing you.

Here is how to fix it with things you probably already have in your laundry room and kitchen.

The heavy-duty laundry stripping soak

This is the method that works on badly yellowed pillows. Fill a bathtub or large sink with the hottest water your tap produces. Add:

• 1/4 cup borax (or baking soda if you do not have borax)
• 1/4 cup washing soda (Arm & Hammer Super Washing Soda — in the laundry aisle)
• 1/2 cup laundry detergent — the regular kind, not the gentle kind

Submerge the pillows and agitate them with your hands for a few minutes. The water will turn brown-yellow almost immediately — that is all the body oils and sweat releasing. Let them soak for four to six hours, stirring occasionally. Drain and rinse thoroughly. Wash in the machine on a normal cycle with no detergent — the pillows are already saturated with cleaning agents. Dry completely — damp pillows grow mildew and that is a worse problem than yellowing.

The hydrogen peroxide and dish soap spot treatment

If the whole pillow is not yellow — just a few spots — this is faster:

1. Mix equal parts hydrogen peroxide (3%) and blue dish soap in a spray bottle.
2. Spray the yellow areas until damp — not soaked.
3. Sprinkle baking soda over the sprayed areas. It will fizz. That is the peroxide reacting and lifting the stain.
4. Let it sit for an hour. Brush off the dried baking soda and wash the pillow normally.

The sun bleaching bonus

Sunlight is a natural bleaching agent. After washing, lay the pillows in direct sunlight to dry. The UV rays break down remaining yellow compounds and brighten the fabric. This is free and chemical-free. It works best on white pillows — colored pillows may fade unevenly in the sun.

Prevention

• Use two pillowcases — a zippered protector underneath and a regular pillowcase on top. The protector catches most of the oils before they reach the pillow.
• Wash pillows every three to six months, not once a year when they are already yellow.
• If you sleep hot or sweat heavily at night, wash pillows more frequently. Some people just produce more body oils and that is fine — you just need to wash pillows more often.

I did the laundry stripping soak on my pillows and they came out white. Not off-white, not beige — white. The water in the bathtub was a color I do not want to describe but my pillows looked new. I now wash them every three months and use a protector case. The yellow has not come back.