It seems simple enough: You’re sick, your friend has some extra prescription medication that is just going to go to waste … so why not put it to use?

A word to the wise: Don’t do it. Here’s why:

1. Stevens-Johnson syndromeor 'burning from the inside out' — is dreadful

Nineteen-year-old Yaasmeen Castanada was feeling under the weather and took some of her friend’s antibiotics. She has been in the ICU burn unit ever since due to a serious reaction to the medication, known as Stevens-Johnson syndrome, in which the skin and mucous membranes burn, blister and shed. Seventy percent of her body has been damaged, according to her mother, Laura Corona. Corona is speaking out about her daughter's tragedy as a warning to be careful about what you put into your body: "Don't share medication, don't give someone else your medication, don't offer medication,” Corona says.

2. You may not really need it

Antibiotics only work against bacterial infections, not viruses – so don't take your friend’s leftover antibiotics for your cold, because it’s not going to help. You could end up burning from the inside out, or at least with other side effects such as diarrhea or a rash. Furthermore, inappropriate use of antibiotics can lead to increased resistance, making bacteria stronger and harder to fight in the future.

3. You could become even sicker

There are many, many antibiotics out there — the best antibiotic for you depends upon the specific illness you have. A decision your doctor, not your friend, should make. An antibiotic prescribed for someone else might not work for the illness you have and may make it worse by delaying proper treatment and allowing bacteria to multiply.

4. Everyone should finish his own medicine

If you take antibiotics, it’s important to take all of the prescribed dose, even once the symptoms have abated. Stopping early could allow the dwindling infection to remain, resulting in continued illness, which is why people should finish their own medication and not dole it out to friends.

5. Prescriptions are prescribed with one person in mind

Medications are prescribed for your particular ailment, and they also dosed for your size and condition. Someone else’s prescription could be completely wrong for you. Also, some stronger drugs are given in smaller doses initially and should be gradually built up – if you take a friend's dose that is on the strong end, you could wind up in trouble.

6. The potential for negative drug interactions is high

Prescription drugs are powerful and don’t always play well with other substances in your body. Mixing certain drugs with certain foods, drinks, dietary supplements and other medications can have devastating effects. Randomly taking someone else’s medication can add to this risk.

7. There is no medical oversight of the risks, so you could die!

All drugs come with the potential for adverse side effects, but the risks that come with prescription medications are overseen by your doctor. If you take medication not prescribed by your doctor, those risks aren’t being managed. When discussing taking other people's medication, the FDA notes, “a person can die from respiratory depression from misusing or abusing prescription painkillers; for example, opioids. Prescription sedatives like benzodiazepines can cause withdrawal seizures. Prescription stimulants such as medications for attention deficit hyperactivity disorder (ADHD) can lead to dangerous increases in blood pressure.”

And if all of that wasn’t enough, we leave you with ABC’s report on Castanada's situation:

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