Why is an overdose fatal? It depends on the type of drug, but opioids, which are the most common form of drug, cause death because of a lack of oxygen.
When we talk about an overdose, we are typically talking about someone who has taken too many of a particular type of drug. This could be by accident or it could be suicide. However, you can overdose on anything that you can eat or drink. The difference is, if you want to overdose on something like coffee, you would have to drink so much that it is not physically possible to do. 180 mg/L of caffeine will kill you, depending on your body size. There I roughly 100 mg of coffee in a cup of coffee, which raises your blood caffeine levels by 5 mg/L. You would have to drink more than 40 cups of coffee for it to be fatal, and you would have to do that in about an hour because your body is constantly removing the caffeine. That’s about 8 liters of coffee in an hour. I’m no saying it couldn’t be done, but it wouldn’t be easy. It is easier to overdose on alcohol, but again, you would need to drink a lot and very quickly. As we drink alcohol, our liver is constantly removing it at the rate of roughly one alcoholic drink an hour. You need about 0.4% alcohol in your blood for it to be potentially fatal. One alcoholic drink raises blood alcohol levels by about 0.02%, depending on body size, which means drinking about 20 alcohol drinks in a short period of time.
So, what kills you in an overdose? Let’s look at these in order of the most common types of overdose. The most common is alcohol but, as we looked at above, this is not usually because of an actual overdose. People who drink too much alcohol are likely to have accidents and be killed through alcohol-related causes. Alcohol can also cause long term damage, which is technically because of overdosing, but it isn’t what we mean here.
Antidepressants and opioids come next. Opioids are anything made from opium, which includes heroin, morphine, and some painkillers. These are fatal because they suppress the body’s ability to breathe. The receptors in the brain that opioids fit into are also receptors that stimulate breathing. If someone takes too many opioids, they will gradually stop breathing enough. This reduces the oxygen levels in the blood, which reduces the amount of oxygen to the brain and organs, and which is ultimately fatal. It can take a while between overdosing and actually dying, so if the person is found and given oxygen, they have a good chance of surviving.
The next most common type of overdose is from stimulants, such as cocaine, speed, ecstasy, and methamphetamine. These almost have the exact opposite result of opioids. Opium suppresses the body’s natural systems and cocaine stimulates them. Drugs like cocaine hit the brain and stimulate it to produce the neurotransmitter called dopamine. This is the chemical that stimulates our reward system and is one reason why these drugs are so addictive. It also stimulates the production of norepinephrine and serotonin. These are drugs that are produced in our flight or fight response as well and they stimulate the heart. Our blood vessels contract and the heart rate speeds up. People taking these drugs can feel excited and euphoric, but an overdose can be fatal because the heart becomes too stimulated. When the heart rate increases too much and the blood pressure goes up, there is an increased risk of heart attacks, strokes, and seizures, all of which can be fatal. However, the majority of overdoses from stimulants tend to happen because people mix different kinds of drugs.
If someone who has overdosed is found and taken to hospital, they do have a good chance. The first step is to get the remainder of the drug out of the stomach or blood system. A stomach pump can be used, but activated charcoal is also used. This can absorb the toxin and stop the body fro absorbing it. Fluids will be given and medication to control blood pressure. Depending on the drug that the person has overdosed on, there are different types of medication. A drug such as naloxone can deactivate opioids and restore regular breathing. There are drugs to deactivate stimulants as well. The sooner a person can get to a hospital, the greater their chance of survival. And this is what I learned today.
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Sources
https://clinicalexcellence.qld.gov.au/sites/default/files/2018-02/overdose.pdf
https://my.clevelandclinic.org/health/diagnostics/22689-blood-alcohol-content-bac
https://www.banyantreatmentcenter.com/blog/how-cocaine-affects-the-nervous-system
https://www.transcendrecoverycommunity.com/blog/can-you-survive-an-overdose-without-medical-help
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