How to Remove Urine Stains
Only enzyme (biological) detergent works. Regular detergent cannot dissolve uric acid crystals. Cold water only — hot water permanently bonds the stain. Never tumble dry before the smell is completely gone.
Why Urine Is Difficult
Urine is a complex mixture: water, urea (a nitrogen compound), uric acid, creatinine, salts, and in some cases bilirubin (which causes yellow colouration). The staining and odour problem is primarily driven by two components. First, uric acid — unlike most other waste products, uric acid is insoluble in cold water and forms persistent crystals that embed in fabric fibres. Standard detergent cannot dissolve these crystals. Only protease and urease enzymes, found in biological ('enzyme') detergents, break the uric acid down into soluble compounds. Second, bacteria on the fabric metabolise urea into ammonia through urease activity — this is the source of the sharp ammonia smell that develops on fabrics left to dry without treatment. Hot water denatures the uric acid proteins and permanently bonds them to fibres, exactly as it does with blood or egg — making the stain significantly harder to remove.
Fresh Stain — Step by Step
Blot immediately — do not rub
Blot up as much liquid as possible with clean paper towels or a cloth. Press firmly, lift, press again. Rubbing spreads the urine sideways and pushes it deeper into the weave. For bedding or mattresses, blot repeatedly until no more liquid transfers.
Cold rinse from the back
Rinse with cold water from the back of the fabric, pushing the stain out rather than through. For garments: hold under a cold running tap. For bedding: pour cold water on the stain. NEVER use warm or hot water — this sets the uric acid into the fibres.
Soak in enzyme detergent solution
Mix a biological (enzyme) liquid detergent with cold water. Fully submerge or apply directly to the stain and leave for 30–60 minutes. The protease enzymes need contact time to break down the uric acid crystals. A longer soak (up to 4 hours) is better for stubborn or older stains.
Wash at 40°C with enzyme detergent
Wash with a full dose of biological detergent at 40°C. Avoid 60°C+ for the first wash — high heat can set any remaining uric acid. Once the smell is completely gone, subsequent washes at higher temperatures are fine for cotton and linen.
Check before tumble drying
Smell and inspect the item before putting it in the dryer. If any ammonia smell remains, repeat the enzyme soak and wash. Tumble drying heat permanently bonds any remaining uric acid residue — the stain and smell will not come out afterwards.
Air dry and recheck
Air dry in a well-ventilated space. The smell should be completely absent. If a faint odour persists when dry, it means uric acid crystals remain — soak again. The smell can return on humid days until the crystals are fully removed.
Dried or Old Stain
Cold water soak to rehydrate
Dried uric acid crystals must be rehydrated before enzymes can work on them. Soak in cold water for 30 minutes before applying any detergent. Skip this and the enzyme treatment is significantly less effective.
Enzyme detergent soak — extended time
Apply a concentrated biological detergent directly to the damp stain. Leave for 2–4 hours, or overnight for very old stains. The enzyme needs more time on dried, crystallised uric acid than on fresh stains.
Use a UV light to find hidden spots
Dried urine fluoresces under UV/blacklight — it appears as a yellow-green glow. Essential for locating old stains on bedding, mattresses, or clothing where the stain is not visible in normal light. UV lights are inexpensive and commonly sold as 'pet stain detectors'.
Wash cold, then warm if needed
Start with a 30°C wash. If the smell is still present after drying, wash again at 40°C with a second full dose of enzyme detergent. Never jump straight to 60°C on a dried stain.
Oxygen bleach for persistent yellow discolouration
For white or colour-safe fabrics with lingering yellow marks after the smell is gone, soak in oxygen bleach (sodium percarbonate, e.g. Vanish, OxiClean) for 1–4 hours, then wash normally. Avoid chlorine bleach — it reacts with ammonia residues and produces harmful fumes.
By Surface
Clothing (cotton, linen, polyester)
Full immersion cold soak in enzyme detergent, then machine wash 40°C. Most straightforward substrate.
Bedding (sheets, duvet cover)
Same as clothing. Wash one set at a time — a full drum load dilutes the detergent and reduces enzyme contact time.
Pillows (down or synthetic)
Machine wash gentle cycle at 30-40°C with enzyme liquid detergent. Down pillows need tennis balls in the dryer on low. Fully dry or mould develops inside.
Wool and cashmere
NEVER use enzyme detergent on wool — proteases digest the keratin protein in wool fibre. Use a non-biological detergent with a white vinegar rinse (1 part vinegar to 4 parts water) to neutralise ammonia. Cold hand wash only.
Silk
No enzyme detergent — silk is a protein fibre. pH-neutral detergent, cold water, very gentle hand wash. White vinegar rinse for odour.
Mattress (not machine washable)
Blot up liquid. Apply enzyme spray or mixed enzyme detergent solution. Let sit 15–30 min. Blot up, do not soak through to the foam. Sprinkle baking soda over the damp area, leave 6–8 hours, vacuum up. Fan-dry the surface completely before remaking the bed.
Carpet
Blot up excess. Cold water rinse (do not pour large amounts). Apply enzyme-based carpet cleaner or diluted biological detergent. Leave 10–15 minutes. Blot up, do not rub. Baking soda overnight, then vacuum.
What to Avoid
Hot water
Denatures uric acid proteins and permanently bonds them to fabric. Cold water throughout until the stain is gone.
Non-biological (enzyme-free) detergent
Cannot dissolve uric acid crystals. The stain and smell will persist through multiple washes.
Tumble drying before fully clean
Heat permanently sets any remaining uric acid. The smell will return on humid days and the stain will not come out afterwards.
Chlorine bleach
Reacts with ammonia residues in urine to produce chloramine fumes — harmful to breathe. Also damages coloured and synthetic fabrics.
Enzyme detergent on wool or silk
Wool and silk are protein fibres. Protease enzymes digest the fibre itself, causing permanent damage. Use non-bio detergent on these.
Fabric softener
Reduces enzyme effectiveness on subsequent washes and can mask smell without removing the underlying crystals.
FAQ
How do you remove urine stains from clothes?
Blot up excess immediately. Rinse with cold water (never hot — heat sets the stain). Soak in biological (enzyme) detergent solution for 30–60 minutes. Machine wash at 40°C with a full dose of enzyme detergent. Check for smell before tumble drying — if any ammonia smell remains, repeat the soak. The protease enzymes in biological detergent break down the uric acid crystals that regular detergent cannot remove.
Why do urine stains smell even after washing?
The smell returns because uric acid crystals are still embedded in the fabric. Standard (non-biological) detergent cannot dissolve uric acid — it cleans surface dirt but leaves the crystals intact. On humid days, the crystals rehydrate and the ammonia smell releases again. Solution: soak in biological (enzyme) detergent for at least 2 hours, then re-wash. Smell persisting after drying indicates the cycle needs to be repeated.
Can I use bleach on urine stains?
Avoid chlorine bleach on urine stains. Chlorine bleach reacts with the ammonia compounds in urine to produce chloramine gas, which is harmful to inhale. Oxygen bleach (Vanish, OxiClean, sodium percarbonate) is safe and effective for removing residual yellow discolouration on white or colour-safe fabrics once the smell is fully gone. Do not use chlorine bleach.
How do you get old urine stains out of clothes?
Soak in cold water for 30 minutes first to rehydrate the dried crystals. Apply concentrated biological (enzyme) detergent directly to the wet stain and leave for 2–4 hours or overnight. Machine wash at 40°C. Use a UV/blacklight to locate all affected areas — dried urine fluoresces yellow-green. Repeat the enzyme soak if any smell persists after drying. Old stains may need 2–3 cycles to fully clear.
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