We have all been in that situation, you come home after a long day, take your keys, and go inside, leaving some things in your car, thinking that you will come back and get them. Our cars tend to turn into a portable, mobile storage unit, which we apparently keep safe and available at all times. It is painless and in the case of many things that people use in their day to day activities a quick trip in the car may be okay.

Nevertheless, this apparently harmless practice contains a rather unexpected number of dangers, both in the form of the possible loss of money and health risks and the severe safety issues. Blistering heat in summer or biting cold in winter can turn the inside of your car into a place that actually damages or even makes useless many of the things you use on a regular basis. Besides, the illusion of safety of a car with a lock might be a sham, because visible objects, or the presence of some bags, can make your car a perfect target of opportunistic robbers.

Reader’s Digest has uncovered these little known perils and has pointed out that even the smallest negligence can expose you to danger. Eva Velasquez, the CEO of Identity Theft Resource Center, notes that it is so easy to slip up and expose oneself to security threats, not only of valuables, but also of personal information. In an effort to assist you in protecting your possessions, your health and your peace of mind, we have created a list of 15 things that you should never leave in your car, at least not over a long period of time.

1. Medication

Most of us have our daily medication or even a backup supply in the car so that we can access it anytime, but this habit is actually a health hazard. The majority of medicines are developed to be kept at room temperature, which is a moderate temperature that your car hardly ever has after parking. The interior temperature can vary wildly as soon as you switch off the air conditioning, or when the weather changes to a colder one, and the temperature can be far out of the ideal range of storage conditions.

Medication heat-sensitivity highlights:

• The temperature of cars is usually very high and does not comply with safe storage standards.
• Heat and cold exposure may cause chemical instability in most drugs.
• Weakened drug potency may cause ineffective treatment or health hazard.
• Particularly vulnerable are medicines such as insulin and antibiotics.

High temperatures, e.g. will not normally cause your drugs to be directly toxic in any toxic sense, but they may seriously diminish their efficacy. Most drugs (including vital ones such as insulin) have a chemical structure that deteriorates quickly at high temperatures, leaving you without it at the very time you need it the most. On the same note, antibiotics may lose their effectiveness, that is, they will not be able to fight infections as expected.

On the other hand, their composition and stability can also change depending on the freezing conditions. This implies that the drug you have left in your car believing that it is always available when you are may fail to give the therapeutic effect you are supposed to get which may cause health related complications or may require you to buy another costly replacement. Never leave your prescriptions and over-the-counter remedies outside in your car or in your house because it is always important to have them with you and keep them in a regulated area.

2. Electronics

In the modern world, it seems that we can never be without our gadgets such as laptops, cell phones, tablets and even thumb drives. Nevertheless, it is a two-fold risk to leave these costly and data-heavy electronics in your car: extreme temperatures damage and direct theft. These devices have delicate parts and, in most cases, lithium-ion batteries that are extremely susceptible to the harsh environment that a parked car is subjected to.

Key protection points of the devices:

• Battery may swell, leak or be permanently damaged by high heat.
• Very low temperatures lower the capacity of batteries and can damage internal circuits.
• Electronics that are not packed away are the easiest to steal through smash-and-grab.
• Data encryption provides a much-needed security in case of theft.

Batteries may overheat in high heat, which may result in swelling, leakage, or even explosion in exceptional situations, destroying the device and the interior of your car. Although a full-blown explosion may not happen, prolonged heat may cause internal parts to be bent, permanently reduce battery life, and reduce screen quality. Conversely, extreme cold may also reduce battery life and ruin fragile screens, rendering your devices unreliable or even useless.

In addition to the physical destruction, electronics are also the favorite of thieves. Velasquez cautions that gadgets that hold personal data are simple to steal when they are left in your car and replacing them is not only costly, but also the data stored in them might be stolen. Although it is always better to leave them with you, in case you really need to leave a laptop or a phone unattended in your car, Velasquez highly recommends that the data stored in it should be encrypted. She observes that it is a good shield, and would require a person to put a lot of effort in it to see, and that it is far more resistant than password protection. You should always make it a habit to carry your devices or keep them locked in a place that is not easily seen or in an area that is controlled by temperature.

3. Sunscreen

It’s ironic, isn’t it? The same product that is meant to shield you against the sun is left exposed to the elements of the sun in your car. Sunscreen, which is an important product in the prevention of burns and skin cancer, has active ingredients that are very sensitive to high temperatures. These protective chemicals start to degrade when a tube or bottle of sunscreen is left to bake in a hot car.

Core points of sun protection storage:

• Exposure to heat lowers the SPF performance.
• Worn out sunscreen can provide minimal or no UV protection.
• Packaging may undergo deformation or burst in case of high temperatures.
• Safety and performance of the product are maintained through proper storage.

This degradation seriously diminishes the effectiveness of the sunscreen and you end up thinking that you are safe when you are actually not. Using defective sunscreen may expose your skin to the sunlight, which may cause painful sunburns and chronic skin damages. Hence, you are defeated by the very reason why you have purchased it in case it is not stored in the correct way. Moreover, the physical integrity of the sunscreen container is in danger, as well. Hot weather may lead to warping, cracking or even explosion of the bottle because of swelling contents. This may leave a sticky greasy mess all over the interior of your car, which may destroy upholstery and need a hard-to-clean clean up. To have your skin indeed protected, it is always best to keep your sunscreen in a cool bag or carry it around. Cover it with a towel even at the beach or the pool to protect it against direct heat.

4. Water Bottles

The common thing to do with plastic water bottles is to leave them in your car, particularly on a hot day but this has some worrying health and safety consequences. Research has attributed such serious health conditions as cancer, heart disease, and diabetes to chemicals such as BPA (Bisphenol A) and phthalates, which are common in plastic water bottles. These chemicals, together with microplastics, can leak into the water you are going to drink when these bottles are heated in the sun-baked interior of your car.

Water safety takeaway points:

• Heat increases the rate of leaching of the chemicals into the drinking water.
• Partially used bottles that are kept at warm temperatures may promote the growth of bacteria.
• Long term use of contaminated water can be dangerous to health.
• Rare instances indicate that bottles have the ability to focus on light and trigger car fires.

There may be long-term health hazards of consuming this chemically contaminated water in the long term. Furthermore, when the bottle is opened and half consumed, the hot stagnant atmosphere of a car provides a perfect environment in which bacteria can grow. It implies that a half-full bottle of water that has been lying in your car since time immemorial may get contaminated, and it may be unsafe to drink it and may even lead to disease.

There is also an unanticipated safety hazard besides health issues. A plastic water bottle can, under some circumstances, serve as a magnifying glass, concentrating the sun on flammable substances in your car. Yes, car fires have begun thus! Although it is not common, it is a shocking reminder of the unexpected threats. To prevent such risks, you should remember the expiration date on the bottled water, and you should always use a reusable, BPA-free, insulated, stainless steel bottle in case you need to have hydration at hand and safe in your car.

5. Credit Cards, Cash, Wallets, and Handbags

Placing a handbag, wallet, or even loose cash and credit cards in an open place inside your car is literally a welcome mat to thieves. You may have locked your doors, or may think there is nothing to steal in your car, but the sight of a bag is enough to make your car the object of an attack. Concerning a visible bag as Eva Velasquez has concisely explained, it does not matter whether the alarm is set off. It looks good and they are going to pick it up.

Theft risk awareness points:

• Observable property is a big contributor to the probability of break-in.
• Thieves are fast in their actions even during the day or in the open places.
• Stolen wallets may cause identity theft and account fraud.
• Prevention: It is easy to avoid it: hide or take away all valuables.

Crooked thieves are always seeking an easy prey and a wallet or handbag in full view is a signal which cannot be ignored. Not even spare change in a cup holder is too much to attract someone to break into your car. It is not only the stolen money or the bag itself but the broken window, the possibility of identity theft in case of credit cards or IDs theft and the inconvenience of having to replace all of that.

In addition to the direct monetary loss, the process of recovering the damaged bank accounts and personal data can be a major burden, and it takes hours to fix. The simplest and most effective action to prevent car theft and discourage such incidents is to simply leave all the valuables out of sight. Better still, it is best to get into the habit of always carrying your wallet, handbag and other money with you when you leave your car, so that they do not get into the hands of another person, who has an easy time taking them.

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6. Glasses (sunglasses and prescription)

Eyes should be protected, and to most people, this involves the use of prescription glasses or sunglasses. It is tempting to leave them in the special compartment of your car or just leave them on the dashboard. Nevertheless, the unstable temperatures in the interior of a parked car can cause havoc to both frames and lenses causing expensive damage and impaired vision.

Eyewear care points:

• Plastic frames can be distorted by heat and comfort, and fit can be distorted.
• Metal frames may get very hot and dangerous to work with.
• The coatings on lenses can bubble, peel or cloud due to long-term exposure to heat.
• Placement of dashboard focuses heat and causes more damage.

Plastic frames are easily distorted under high heat particularly in warmer seasons and this makes them lose their shape and fit poorly. Metal frames may get so hot that they cannot be touched, and it is impossible to wear them. What is more important, the lenses are prone as well. Lensscoatings may peel or form bubbles due to heat and this will impair your vision and make the glasses useless. Such repairs or replacements are quite costly.

It is especially problematic to leave the glasses or sunglasses on the dashboard. The windshield may be a magnifying glass, and it may focus the sunlight and increase the amount of heat on your eyewear. This will increase the damage and in severe cases, may even become a small fire hazard should the light be directed towards a flammable surface. Although the sunglasses compartment of your car is good in the short-term, it is always better to take your glasses and sunglasses out of the car as soon as you arrive at your destination and keep them in a more temperature-neutral place to increase the life of the product and keep it working.

7. Necessary documents (passports, tax forms, birth certificates)

Consider your own document like passports, birth certificates, financial statements, tax forms, school transcripts – as physical identifications of who you are. Even taking these important papers in your car to run some errands even in a short period of time is a huge security risk. In case someone breaks into your car, these documents are easily misplaced in wrong hands, and you become extremely susceptible to identity theft and fraud.

Key points of identity security:

• The documents theft may result in identity fraud in the long term.
• Passports are especially useful to the criminals.
• Paper is prone to warping or rotting during heat and humidity.
• Personal data needs to be secured just like treasures.

Eva Velasquez highlights how dangerous this threat is, and identity theft may be even easier to commit using a passport than a driver license. She challenges us to rethink our understanding of these objects: we need to think of the information and bits of our identity as treasures. You will not leave jewelry in the car, but we do not have the same concern with things that constitute our identity, and we must. This points out a vital negligence of most of us, who put the material things above the immaterial, but equally important, aspects of our personal information.

In addition to the danger of theft, such sensitive papers can also be affected by environmental degradation in your car. Paper may also curl, crack or even wear out with time due to high heat and humidity resulting in inability to read or handle them. When you have papers to shred or mail, then it must be on your to-do list to ensure that they are done first. Velasquez tells him, Leave it in the car, take care of it and you are done. You have to follow through.” The moral of the story is simple, unless these documents absolutely must be in your car at that particular time they are much better at home or in the office, safely locked away.

8. Wine

Most of us love to relax with a glass of wine, however, when you are going to the store, you must ensure that wine is the last thing before going home. The inside of a car, particularly in the summer season, is hardly the right place to keep a bottle of your favorite vintage. A few minutes of heat may cause havoc on its delicate balance, and turn it into something much less pleasant.

Highlights of wine temperature sensitivity:

• The internal pressure due to heat may loosen the cork.
• Warm temperatures increase oxidation and spoil taste.
• Spoiled wine can also become brown and acquire vinegar-like aromas.
• The stability of temperature is essential in maintaining the quality of wine.

When a bottle of wine is overheated, the air in it starts to expand and causes tremendous pressure on the cork. It is not a small problem, when the cork is loose or pushes out, even in the smallest way, it opens a way to oxygen and undesirable bacteria to enter the bottle. This is referred to as oxidation and it can easily spoil the wine, permanently changing its taste and smell, a sure indication that your wine has gone bad.

It is true that a hot cabin is the formula of spoiling a great wine. The faster the oxidation process, the higher the heat, the more likely your wine will appear brown and acquire an off-flavor, which is reminiscent of vinegar. This is because of your well-selected bottle, which you thought was to be a relaxing evening, but it could end up in the drain. In order to enjoy your wine, you should always make sure that you pick it up after work or any other errands so that it can be taken out of the store to a place where it is not subject to temperature change as fast as possible.

9. Young children

This is not about convenience, this is life and death. Although you may think that an errand will take just a few minutes, when you leave young children alone in a car, especially on a hot day, you are putting them in the danger of extreme and fast escalating risks. According to the Centers of Disease Control and Prevention (CDC), temperatures in vehicles may rise almost 20 degrees within 10 minutes, despite leaving a window open, which poses an immediate and serious threat of heatstroke.

Child safety warning points:

• Heatstroke may develop quickly even during warm weather.
• The body of children heats up very quickly as compared to that of adults.
• There are dozens of child deaths every year due to heat.
• In most states, it is against the law to leave kids in cars unattended.

The statistics are sobering. As many as 39 children lost their lives in 2024 alone due to being left in a car because of heatstroke. This is two times more than the national average, which highlights the urgency of being on the alert all the time. What may appear to be a short period may result in a lethal mistake because the body temperature of a child may increase three to five times as rapidly as that of an adult, and thus they are much more vulnerable to heat-related diseases.

In addition to the direct health risk, it has legal consequences. It is also essential to know your state laws as in most places it is against the law to leave young children unattended in a vehicle even though it may be hot outside. Although the weather may not be scorching, the danger of being kidnapped, accidentally operating vehicle controls, or even just being scared and upset on behalf of the child are enough to make you always carry them along.

10. Pets

Similar to small children, our favorite pets are extremely sensitive to the extreme weather changes in a parked car. It is a sad fact that hundreds of pets are killed each year due to overheating in cars, which is a heartbreaking fact as stated by the American Veterinary Medical Association. The notion that opening a window or parking in the shade provides adequate security when traveling with pets is a harmful illusion.

Pet heat safety overview:

• The temperature inside the car may be more than 40 degrees higher than the temperature outside.
• Cracked windows do not offer any significant cooling.
• Pets do not cool effectively by panting, and this exposes them to heat.
• Heatstroke in animals may result in irreversible organ damages or death.

Even in what may appear like a cool climate, the inside temperature of a car may rise by 45 degrees above the exterior climate in only an hour. A shaded parking space does not provide much relief as it does not reduce the heat accumulation that transforms a car into a death trap to animals. Pets do not sweat as humans do, they cool themselves mostly by panting, which is not very effective in hot weather.

The effects of leaving an animal in a hot car can be disastrous as they cause irreversible organ damage, brain damage, and even death. This exposes pets to great danger and highlights the fact that pets should never be left unattended in a vehicle. Also, it is important to mention that frightened or frightened pets may become aggressive, which can lead to the destruction of the interior of your car, including scuffs and scratches on leather and plastic. You should always bring your furry friends and make sure that they are safe and comfortable.