Sanitize Cycle Washing Machine: What It Does and When to Use

You are standing at the washer, care label in hand, staring at a button marked Sanitize. You know it kills germs. What you do not know is whether it will also cook your favorite sweater into a doll-sized version of itself. That hesitation is the whole reason this setting confuses people. The sanitize cycle washing machine setting is genuinely useful, but only for the right loads, and it can quietly ruin the wrong ones.

I test laundry settings for a living, and I have shrunk enough merino to learn the boundaries the hard way. This guide explains exactly what the sanitize cycle does, when it earns its place, when to skip it, whether it costs you extra on the utility bill, and whether you still need a separate sanitizer additive. I cite NSF, the CDC, and the EPA throughout, so you can check the claims yourself.

What the sanitize cycle actually does

A sanitize cycle (sometimes labeled “Sanitary” or “Allergen”) is a specialized wash program built around one idea. Heat kills microbes. On most home washers, it heats the wash water to roughly 150 to 165 degrees Fahrenheit (about 65 to 74 degrees Celsius), which is 20 to 40 degrees hotter than a standard “hot” wash. It then holds that heat and runs a longer wash and rinse so the elevated temperature has time to do its job.

Three things happen during the cycle:

1. The washer heats the water past what your tap can deliver. Most household water heaters are set around 120 degrees Fahrenheit, so a sanitize cycle relies on an internal heater in the machine to push past that.
2. The wash and rinse phases run longer. Bacterial kill depends on both temperature and time (thermal dwell), so the cycle extends both.
3. Extra rinsing flushes the drum. A longer or extra rinse, and on some models a purge, helps clear loosened microbes and residue out of the tub.

If you want the underlying science of why heat works and what each temperature threshold accomplishes, I break it down in what temperature kills bacteria in laundry. The short version: warmth alone is not enough. Sustained high heat is what matters.

What “sanitize” is certified to mean (NSF Protocol P172)

Here is a detail most articles get wrong, so read carefully. The standard that applies to clothes washers is NSF Protocol P172, not NSF/ANSI 184. NSF/ANSI 184 is the standard for residential dishwashers, which requires a 99.999 percent (5-log) bacterial reduction and a 150-degree final rinse. Those are different appliances with different numbers.

For clothes washers, NSF’s washer and dryer certification confirms that a machine tested under Protocol P172 must reduce 99.9 percent of microorganisms on the sanitization cycle, with no significant carryover of bacteria into the next load. The protocol simulates heavy contamination on a small number of items inside an otherwise normal load, then verifies that at least 99.9 percent of the test organisms are removed.

One nuance is worth knowing. Protocol P172 does not lock in a required water or steam temperature. It judges the finished result. A washer can reach the 99.9 percent target through its own combination of heater wattage, cycle time, temperature, and tumbling action, as long as the sanitization is proven. That is why two certified washers can run their sanitize cycles differently and both pass.

So when a washer carries the NSF mark for sanitization, “sanitize” is not marketing language. It is a measured, third-party-verified 99.9 percent reduction. A machine without that certification may still have a “sanitize” button, but the performance is not independently confirmed.

Standard	Appliance	Bacterial reduction	Key requirement
NSF Protocol P172	Clothes washer	99.9% (3-log)	Verified result, no carryover; no fixed temperature
NSF/ANSI 184	Dishwasher	99.999% (5-log)	150 degrees F final rinse
CDC healthcare laundry guidance	Any washer	Effective microbial reduction	160 degrees F for at least 25 minutes

The CDC’s guidance on laundry and bedding recommends a hot-water temperature of at least 160 degrees Fahrenheit (71 degrees Celsius) for a minimum of 25 minutes to reliably destroy microorganisms. That is the healthcare benchmark, and it is why a proper sanitize cycle runs hot and long rather than fast.

When you should use the sanitize cycle

Use it when the health benefit is real and the fabric can take the heat. Good candidates include:

• Bath and hand towels, especially ones that have gone sour. Persistent mustiness is bacterial. If normal washing no longer fixes the smell, a sanitize cycle often does.
• Bedding and pillowcases after illness, when someone in the house has had the flu, a stomach bug, or a skin infection.
• Cloth diapers, which need occasional deep sanitizing, particularly after a yeast or fungal rash.
• Sturdy cotton underwear, workout cotton, and kitchen cloths that contact raw food.
• Reusable cleaning rags that mop up messes all week.

Two of those deserve a note. For cloth diapers, sanitizing guidance is specific. Use it occasionally, not every wash, and if you bleach, use plain disinfecting bleach (at least 5.25 percent sodium hypochlorite), never splash-less or scented versions. Always rinse and follow with a hot detergent wash to break the bleach down. Routine hot washing handles day-to-day cleaning. Sanitizing is for reset situations.

For a broader walkthrough of germ-killing wash routines, including the difference between simply cleaning and truly sanitizing, I keep a full pillar at how to sanitize laundry. That page is the companion to this one.

Does the sanitize cycle shrink clothes?

Now the part you came for. The sanitize cycle can shrink clothes, and it can also degrade fibers in ways that are not reversible. High heat is exactly what these materials are not built to handle.

Avoid the sanitize cycle on:

• Wool, cashmere, and merino. Heat, moisture, and agitation together cause the microscopic scales on wool fibers to open and interlock, a process called felting. That is permanent shrinkage. Wool should be washed cold, gently, or by hand.
• Elastane, spandex, and Lycra blends. Excess heat makes these fibers lose elasticity and can leave them brittle. Think leggings, activewear, swimwear, shapewear, and the stretch waistbands in many garments. The stretch never fully comes back.
• Silk and other delicate protein or specialty fibers, which can weaken, pucker, or discolor.
• Anything with glued seams, foam, elastic trims, or heat-sensitive prints and appliques, which can delaminate or peel.
• Loosely knit or already-fitted cotton you cannot afford to lose a size on. Even cotton shrinks when it has not been pre-shrunk.

The rule I live by: read the care label first. If it says wash cold, tumble low, or “do not use hot water,” the sanitize cycle is off the table. When in doubt, treat the item as delicate and use a sanitizer additive in a cool wash instead (more on that below). This is a case where the germ-killing benefit is not worth the risk to the garment.

Does the sanitize cycle use more energy and water?

Yes. There is no free lunch here. The cycle’s defining feature is heating water well past your tap temperature, and heating water is the single most energy-intensive thing a washer does. It accounts for the large majority of the electricity a washer draws. The internal heater in a front-load washer commonly pulls somewhere between about 900 and 1,500 watts while it works, and the sanitize cycle runs that heater harder and longer than any other setting.

Expect three practical costs:

• More electricity, from the internal heating element bringing water to 150-plus degrees.
• More water, from the extended and extra rinse phases.
• More time. A sanitize cycle commonly runs 90 minutes to about 2 hours, versus 45 to 60 minutes for a normal wash.

None of that is a reason to avoid it. It is a reason to use it deliberately. Reserve it for loads that genuinely need sanitizing rather than making it your default. For everyday laundry, a normal warm or cold wash with good detergent is plenty.

Do you still need a laundry sanitizer additive?

It depends on your machine and your load. If your washer has an NSF-certified sanitize cycle and the fabric tolerates high heat, the cycle alone meets the 99.9 percent standard, and you do not need an additive. Heat is doing the work.

You want an additive in three situations:

1. Your washer has no sanitize cycle, which is common on older and budget machines.
2. The fabric cannot take the heat (wool, spandex, delicates), so you need to disinfect in a cool wash.
3. You want an extra margin of safety, which the CDC notes bleach provides.

The most familiar option is Lysol Laundry Sanitizer, which is EPA-registered (EPA Reg. No. 777-128) to kill 99.9 percent of bacteria, including Staphylococcus aureus and Klebsiella pneumoniae, in the rinse cycle. It contains no chlorine bleach, works in cold water, and is added to the rinse, which makes it a reasonable choice for colors, darks, and heat-sensitive fabrics. If you want the step-by-step, I wrote how to use Lysol Laundry Sanitizer, and I compare the leading options in the best laundry sanitizers.

A quick note on temperature and chemistry. The CDC points out that low-temperature wash cycles rely heavily on chlorine- or oxygen-activated bleach to reduce microbial contamination, and chlorine bleach becomes active between about 135 and 145 degrees Fahrenheit. In other words, a cold wash disinfects through the additive, not the water, which is exactly why these rinse-cycle products exist.

Which washing machines offer a sanitize cycle?

Most major brands include one on their mid-range and higher front-load and top-load models. NSF maintains a public list of certified appliances, and the brands with certified washers include GE, Whirlpool, Maytag, Bosch, Samsung, Electrolux, and LG.

A few real examples from manufacturer documentation:

• LG front-load models offer a “Sanitary” high-temperature cycle that reduces bacteria, and some add an Allergiene steam cycle aimed at dust-mite allergens.
• GE washers pair a sanitize cycle with an oxygenated additive dispenser (labeled Oxi on some units) and reach elevated wash temperatures.
• Whirlpool and Maytag use high-temperature sanitize cycles marketed to remove 99.9 percent of common household bacteria.
• Samsung front-loaders include a sanitize option, often with steam, on many current models.

If you are shopping, look specifically for the NSF certification mark rather than just the word “sanitize” on the panel. The mark is your assurance the 99.9 percent figure was tested, not assumed. You will also find replacement washer-cleaning tablets and rinse-cycle sanitizers from these same brands in stores and online. Choose by reputable name, and always match the product to your fabric.

Do not forget the machine itself

A sanitize cycle cleans your laundry, not the drum, gasket, and detergent drawer where mold and bacteria actually live. Front-loaders are especially prone to a musty biofilm behind the rubber door seal. Run a dedicated tub-clean or “clean washer” cycle roughly monthly with hot water and a washer cleaner such as Affresh, wipe the gasket with a diluted bleach solution while wearing gloves, pull out and rinse the detergent drawer, and leave the door ajar between loads so moisture escapes. A clean machine is what keeps freshly sanitized laundry from picking up odor on the way out.

If odor is your core problem, vinegar has a real but limited role in laundry, useful for softening and cutting some residue but not a reliable disinfectant on its own. For the full range of hygiene topics, from towels to bedding to fabric care, browse the laundry and textile hygiene hub, part of the wider Sanitation Towel resource.

The bottom line

The sanitize cycle is a legitimate tool, not a gimmick. On an NSF-certified washer it delivers a verified 99.9 percent reduction in bacteria by heating water to around 150 to 165 degrees Fahrenheit and holding it there. Use it for towels, post-illness bedding, cloth diapers, and heat-tolerant cottons. Skip it for wool, spandex, silk, and anything the care label wants kept cool, and reach for a cold-water sanitizer additive instead. Expect it to use more energy, water, and time, so run it with intent rather than by habit.

This article is general hygiene guidance, not medical advice. If you are managing laundry for someone with a contagious infection, a weakened immune system, or a wound, follow the instructions from your doctor or your local health authority, which may call for specific temperatures, bleach concentrations, or handling steps beyond what a home cycle provides.

Frequently asked questions

Does the sanitize cycle shrink clothes?

It can. The cycle heats water to about 150 to 165 degrees Fahrenheit, and that heat felts and shrinks wool, weakens elastane and spandex, and can shrink un-preshrunk cotton. Sturdy cotton towels and bedding are safe, but delicates, activewear, and wool should never go through it. Always check the care label first.

What does the sanitize cycle do that a normal hot wash does not?

A normal hot wash uses your tap hot water, usually around 120 degrees Fahrenheit, which cleans but does not reliably kill most bacteria. The sanitize cycle uses an internal heater to push water to roughly 150 to 165 degrees, then holds that heat over a longer wash and rinse. On an NSF-certified washer this achieves a verified 99.9 percent reduction in microorganisms.

Is the washer sanitize cycle certified to kill germs?

On certified machines, yes. NSF Protocol P172 requires a clothes washer to remove 99.9 percent of microorganisms on its sanitization cycle with no carryover to the next load. The protocol judges the result rather than mandating a fixed temperature. Look for the NSF mark rather than just the word 'sanitize' on the control panel, since the certification is what makes the 99.9 percent figure independently verified.

Does the sanitize cycle use more energy and water?

Yes. Heating water is the most energy-intensive thing a washer does, and the sanitize cycle runs the internal heater harder and longer, drawing roughly 900 to 1,500 watts while it heats. It also adds rinse phases, so it uses more water and typically runs 90 minutes to 2 hours. Use it only for loads that genuinely need sanitizing.

Do I still need a laundry sanitizer if my washer has a sanitize cycle?

Not for heat-tolerant loads on a certified machine, since the heat does the work. You do want an additive when the fabric cannot take high heat, when your washer lacks a sanitize cycle, or when you want extra safety. Rinse-cycle products like Lysol Laundry Sanitizer are EPA-registered to kill 99.9 percent of bacteria, contain no chlorine bleach, and work in cold water.

Can I use the sanitize cycle on cloth diapers?

Yes, occasionally, but not for every wash. Cloth diapers benefit from periodic deep sanitizing, especially after a yeast or fungal rash. If you add bleach, use plain disinfecting bleach at 5.25 percent sodium hypochlorite (not scented or splash-less), then rinse and follow with a hot detergent wash to break the bleach down. Routine hot washing handles everyday cleaning.