1. Different battery brands
Mixing batteries from different brands can lead to them leaking battery acid. The reason is that manufacturers use different chemical compositions for their batteries, which produce different levels of current. When one runs out of juice, the other can still keep running, but this causes it to leak, eventually damaging electronic devices and creating a health hazard.
2. Rubbing alcohol & bleach
Rubbing alcohol contains ethanol or isopropyl alcohol, which, when mixed with household bleach containing sodium hypochlorite, will create chloroform and hydrochloric acid, as well as chloroacetone or dichloroacetone. These compounds can cause damage to the nervous system, lungs, kidneys, liver, eyes and skin. Also, high levels of chloroform can lead to dizziness, nausea, loss of consciousness and even death.
3. Ammonia & bleach
This combination is also very dangerous, producing vapors that can cause severe damage to your respiratory system. And that’s not the worst thing that can happen – if there are large amounts of ammonia, you might create a substance called liquid hydrazine. Liquid hydrazine is highly toxic and potentially even explosive.
4. Vinegar & bleach
If you add a weak acid to bleach, it creates vapors of toxic chloramine and chlorine. These vapors can cause serious chemical burns to your eyes and lungs.
5. Vinegar & baking soda
Vinegar is an acid and baking soda is a base – these two cancel each other out, rendering the resulting solution useless. This one isn't dangerous, it's just a waste of useful materials.
6. Vinegar & hydrogen peroxide
Combining these two products in the same container will create a corrosive peracetic acid. In high enough concentrations, peracetic acid can irritate and even damage your skin, eyes, throat, nose and lungs.7. Grapefruit & certain medicines
Compounds in grapefruits interfere with enzymes in the stomach, which are in charge of metabolizing certain types of medicine. This ends up increasing the level of certain chemicals in the blood and can lead to a deadly overdose.
8. Alcohol & Ibuprofen
Taking ibuprofen on an empty stomach can damage the stomach lining. Adding alcohol into the mix stimulates this process and can worsen the effect. Damage to the lining can lead to internal bleeding, ulcers and other stomach problems that can become chronic.
9. Alcohol & acetaminophen
Chronic consumption of alcohol causes the body to produce certain enzymes that adversely interact with acetaminophen. The reaction can damage the liver and can even be lethal. In the U.S. alone, over 200 people die every year due to this deadly combination.
10. Dairy & antibiotics
Dairy is rich in calcium, and while it may be good for your bones, its interaction with antibiotics is anything but. Calcium prevents the antibiotics from being absorbed into your body, reducing their effectiveness. Antibiotics that are most affected by dairy are: ciprofloxacin, levofloxacin and tetracycline.
11. Milk & energy drinks
The acid in energy drinks mixes with proteins in the milk, causing the milk to curdle very quickly. The result is usually projectile vomiting.
Both of these skincare products may help you look younger, but mixing them together is a bad idea. Glycolic acid has a different level of pH than retinol, so when both are used, the glycolic acid becomes dominant, reducing the effectiveness of retinol considerably. It can also cause some skin irritation.
13. Retinol & sunlight
Recent evidence shows that retinol can become toxic when exposed to direct sunlight, and can increase your chances of getting a sunburn. It is recommended that you only use it at night, or if you choose to use it during the day – use sunscreen and avoid direct sunlight as much as possible.