Mosquito Liquid Refill: Shelf Life and Storage

How long 45 ml liquid refills last

Mosquito liquid is a seasonal product: households buy several bottles in early summer and often forget about the rest until the following year. The first question is therefore not how to use it, but how long it keeps. Under normal conditions, an unopened PARPAR 45 ml refill has a shelf life of five years. Once opened, it should be used within one summer, usually three to four months.

The difference matters because an opened bottle is no longer sealed. The wick opening lets the liquid evaporate slowly, and the cap seal weakens each time the bottle is moved. A bottle that has been open since last summer may still smell strong, but its release rate is no longer reliable.

Why shelf life matters

The active ingredient changes slowly with time, temperature and light. If the seal is poor, the solvent evaporates first and the remaining liquid becomes more concentrated, which changes the release rate. If the bottle is exposed to high heat, the plastic can soften and the cap seal can age. The result is rarely "completely useless"; more often it is "weaker than expected, and the bottle empties faster".

For a household, the practical question is not the chemistry but the cost of a bad bottle. A refill that has lost strength still looks normal, still smells of mosquito liquid, and still costs the same. The loss shows up as a second bottle bought mid-summer, or as a room that stops feeling protected at two in the morning. Storing three bottles correctly is cheaper than replacing six that were kept on a balcony.

Condition	Recommended use
Unopened, original packaging	Up to 5 years
Opened, in normal use	3 to 4 months, one summer
Opened, left unused over winter	Do not carry over to the next year
Exposed to heat or direct sunlight	Inspect before use; replace if in doubt

How to store refills at home

• Keep them cool, dark and dry, ideally below 25°C.
• Keep the original packaging and cap. Never transfer the liquid into a drinks bottle or water bottle.
• Store away from children, pets, food and drinking water.
• Avoid the kitchen hob, the water heater, a metal balcony cabinet and the car.
• Store upright, not on the side and not upside down, so liquid does not seep into the cap.

Storing in Egyptian summer heat

In Cairo and Alexandria, a balcony or a parked car can exceed 50°C in July and August. Mosquito liquid should not be stored on a balcony, in a car, under a kitchen sink next to a hob, or in a rooftop storage room. The safest places are the lower shelf of a bedroom wardrobe, a living-room cabinet, or an inner shelf in a storage room. If the home has no air conditioning, choose the coolest room in the flat.

For a shop, the same rule applies at a larger scale: keep cartons away from the front window, direct sun and heat-generating equipment. A back shelf is better than a display next to the door.

How to tell if a bottle is still usable

• Bottle: swelling, deformation or leakage.
• Liquid: visible separation, sediment or an unusual colour.
• Smell: a sharp solvent odour or an unusual smell.
• Date: an unopened bottle older than five years is not recommended.
• Performance: if the same room and setting now give noticeably shorter protection, the liquid may have degraded.

When in doubt, replace the bottle. The cost of one 45 ml refill is small compared with a night of ineffective protection.

Rotating household stock

1. First in, first out: put new bottles behind the older ones.
2. Write the purchase month on the bottle base with a marker.
3. Do not stock more than one summer's use; three to six bottles is enough for most homes.
4. Check the storage cabinet once a quarter and use the oldest bottles first.
5. Do not mix bottles from different years in the same box.

Stock rotation for shops and distributors

Storage condition	Check interval	Action
Cool, dark, below 25°C	Every 3 months	Normal rotation
Room temperature, occasionally above 30°C	Every 2 months	Move older stock out first
Near heat or direct sunlight	Every month	Relocate and inspect bottles
New delivery	On arrival	Check for leaks, caps and carton damage

For carton storage, keep pallets off the floor and away from the wall, do not stack cartons too high, and mark the arrival month on the outside of each carton. A simple rotation sheet is enough; the point is to know which carton is oldest without opening every box.

For the number of bottles a household actually needs, see the bottles-per-room guide. The 45 ml refill specification lists the 200-bottle carton, and the liquid versus spray comparison explains the cost per night.

Frequently Asked Questions

Can I use an expired mosquito liquid refill?

It is not recommended. The active ingredient may have degraded and the release rate is no longer reliable, so protection is not guaranteed.

Can I use a bottle that was opened last year?

Do not carry an opened bottle over to the next year. The seal weakens after opening and the liquid may thicken or evaporate.

Does storing the bottle in the fridge extend shelf life?

No. Cool, dark storage at room temperature is enough. A fridge adds humidity, which can affect the cap and wick area.

Why is the bottle half empty if it was never used?

An opened bottle loses liquid slowly through the wick opening. If the bottle itself is leaking or the carton shows oil stains, treat it as transport damage.