Washing blankets can kill fleas, but the wash cycle alone isn’t guaranteed to eliminate every flea at every life stage. The combination of hot water, detergent, and especially a hot dryer cycle is what makes laundering an effective part of flea control. If you skip the dryer or wash on cold, some fleas and their eggs can survive.
Why Water Alone Isn’t Enough
Adult fleas have a hard exoskeleton coated in a waxy layer that repels water. This coating allows them to resist drowning for up to 24 hours or longer in some cases. In a typical washing machine cycle lasting 30 to 60 minutes, some fleas can survive submersion, particularly if they get trapped in folds of fabric where water flow is minimal.
Flea eggs are even trickier. They’re tiny, smooth, and don’t absorb water easily. Eggs and pupae (the cocoon stage before an adult flea emerges) have protective casings that can withstand a surprising amount of moisture exposure. So tossing a flea-infested blanket into a cold or warm wash without detergent would leave you with a damp blanket that still has living fleas on it.
How Detergent Actually Kills Fleas
The real weapon in your washing machine isn’t the water. It’s the detergent. Laundry detergent contains surfactants, compounds designed to break down grease and oils. These surfactants do two things to fleas. First, they dissolve the waxy coating on a flea’s exoskeleton, which is what keeps water out of its body. Once that coating is stripped away, water enters the flea’s respiratory system and drowns it. Second, surfactants reduce the surface tension of the water itself, so fleas can no longer float or resist sinking.
Any standard laundry detergent will work for this purpose. You don’t need a special flea-killing formula. The surfactants in regular detergent are chemically similar to the compounds in dish soap, which is commonly used in DIY flea traps for the same reason.
Hot Water vs. Cold Water
Temperature matters. Hot water (130°F or higher) kills adult fleas, larvae, and eggs more reliably than cold or warm settings. Flea larvae are particularly vulnerable to heat. According to Texas A&M’s entomology extension, temperatures above 95°F kill flea larvae, and the hotter you go, the faster mortality occurs.
If your blanket’s care label allows it, use the hottest water setting your machine offers. For delicate blankets that can only be washed in cold water, the detergent will still help, but you’ll be relying more heavily on the dryer to finish the job.
The Dryer Is the Most Important Step
Running your blankets through a hot dryer cycle for at least 30 minutes is the single most effective step for killing fleas at all life stages, including eggs, larvae, pupae, and adults. The sustained heat inside a dryer on a high setting typically reaches 125°F to 135°F, well above the lethal threshold for every stage of a flea’s life cycle. The combination of heat and tumbling also physically dislodges eggs and larvae from fabric fibers.
If you have blankets or bedding that can’t go in the dryer, consider laying them flat in direct sunlight on a hot day. This is less reliable than a dryer, but fleas and their larvae do poorly in hot, dry conditions. Humidity below 50% combined with temperatures above 95°F is lethal to flea larvae.
What About Bleach or Vinegar?
Bleach (sodium hypochlorite) can kill flea eggs and pupae by breaking down their protective casings and internal structures. However, it has limitations. Mobile adult fleas sheltered in fabric folds may survive, and bleach will damage or discolor most blanket materials. If you’re washing white cotton bedding that can tolerate bleach, a small amount added to the wash cycle provides extra killing power, but it’s not necessary if you’re using hot water, detergent, and a dryer.
Vinegar is sometimes suggested as a natural flea killer in laundry, but there’s no strong evidence it adds meaningful flea-killing ability beyond what detergent already provides. More importantly, never mix vinegar with bleach. This combination creates chlorine gas, which is genuinely dangerous to inhale.
Which Items to Wash and How Often
Fleas lay eggs on their host, but those eggs roll off onto whatever surface the animal rests on. That means your pet’s favorite blanket, your bedding, couch throws, and any fabric your pet regularly contacts are likely harboring flea eggs, larvae, or pupae even if you don’t see adult fleas on them. A single female flea can lay 40 to 50 eggs per day, so infestations build quickly in soft furnishings.
During an active infestation, wash all pet bedding and any blankets your pet has contacted at least once a week. Use the hottest water the fabric allows, add your normal detergent, and run everything through the dryer on high heat for 30 minutes minimum. Don’t forget items people often overlook: pillow covers, area rugs small enough for the machine, and fabric pet carriers.
Why Washing Alone Won’t End an Infestation
Laundering blankets and bedding is an important piece of flea control, but it only addresses the fleas living in washable fabrics. The majority of a flea population in your home (roughly 95%) exists as eggs, larvae, and pupae scattered across carpets, upholstery, and floor cracks. Adult fleas on your pet are just the visible tip of the problem.
To actually eliminate an infestation, you need to treat the pet (with a veterinarian-recommended flea product), vacuum carpets and furniture thoroughly and frequently, and wash soft furnishings on a regular schedule. Vacuuming is especially important because it pulls eggs and larvae out of carpet fibers and, through vibration, stimulates pupae to emerge as adults, making them vulnerable to treatment. Combining all three approaches, treating the pet, vacuuming, and laundering, breaks the flea life cycle at multiple points and prevents reinfestation.