How does an Overdose of Pills Affect the Body and Brain?

Any substance, when consumed in large numbers, may build up in the body and cause harmful symptoms. To prevent overdose on pills, it’s best never to consume prescription drugs in doses not specified by your doctor or as indicated on the package. However, some general recommendations will help you better understand which types of pills can be harmful and how they affect the body and brain. Canadian Centre for Addictions has compiled a comprehensive list of what pills can you overdose on and how to spot the symptoms early.

Types of Overdosing Pills

Most medications contain substances that human bodies can process slowly or can’t process properly. Over time, especially if consumed in large quantities, they build up in tissues and organs, which may cause severe harm. Here are the most potent drugs that should be consumed only under supervision.


Opioids are notoriously addictive due to their tendency to build up in the brain, even when consumed in small numbers. They are often used for treating intense pain, and patients quickly build up a tolerance to them, requiring increased dosage to achieve the same effect. This may cause patients to develop a dependency or overdose quickly. 

The most commonly used opioids are Oxycodone, Hydrocodone, Morphine, and Fentanyl. They are highly regulated but are one of the most illegally distributed drugs, especially Fentanyl. Without medical supervision, individuals are likely to ingest more than their bodies can handle and overdose on pills.

The Effects of Opioid Pills Overdose

Due to the effects of opioids, overdosing on these pills causes a severe decrease in body functions. Individuals often experience trouble breathing and become unresponsive. As they experience respiratory depression, the brain receives less oxygen which causes the loss of consciousness up to a comatose state. Other outside signs are pupils contracting to a pinpoint level and lips and nails turning blue. Without a timely response, affected individuals are likely to fatally suffocate or experience brain death.

Sleep Aids

Sleep aids, both prescription and over-the-counter, have strong sedative effects. When consumed as prescribed, they are harmless, but overdosing on these pills may cause lasting damage or even death. This may happen as a result of negligence or some psychological factors like extreme stress.

The over-the-counter options are Diphenhydramine (Benadryl) and Doxylamine (Unisom). Additionally, some Benzodiazepines like Temazepam (Restoril), Triazolam (Halcion) and Flurazepam (Dalmane) are also sometimes prescribed for normalizing sleep. The latter tend to have more severe effects due to the potency of the core components.

The Effects of Sleep Aid Pills Overdose

The mild signs of an overdose are dry mouth and blurry vision. Sleep aids have a strong sedation effect which can make breathing difficult or put the individual in a comatose state in case of an overdose. Some individuals may be allergic to the components of the medications, which may trigger a strong response, so it’s crucial to consult with medical professionals beforehand. Hallucinations and confusion are also common, potentially leading to trauma caused by accidents.

Over-the-Counter Pain Relievers

Pain relief medications may seem harmless, and it seems unlikely to overdose on them, but it’s not true. When taken in above-than-prescribed doses, pain relief pill overdose may cause intense physical harm to the human body. The reasons vary depending on the type of drug. The main over-the-counter pain relievers are Acetaminophen (Tylenol) and Ibuprofen (Advil, Motrin).

The Effects of Over-the-Counter Pain Relievers Overdose

The human liver processes Acetaminophen very slowly, so in case it’s used in large doses or for a prolonged period of time, it may build up and cause an overdose. Tylenol pill overdose causes long-lasting liver damage or even liver failure. The main symptoms are frequent vomiting, nausea and yellowing of skin and eyes.

Ibuprofen is a strong anti-inflammatory medication that tends to affect the gastrointestinal, renal and cardiovascular systems. Larger-than-prescribed doses disrupt the production of protective gastric mucosa, which may cause ulcers, gastritis or intestinal bleeding. Watch out for strong chronic stomach pain, heartburn, black, tarry stool and vomiting. Ibuprofen overdose also causes kidney damage, potentially leading to permanent disruption of their function and chronic disease. Fatigue, confusion, swelling in the legs and decreased urine output are the most common symptoms. Lastly, Advil and Motrin pills tend to increase blood pressure which causes hypertension and increases the risk of heart attacks or strokes. The first signs are shortness of breath, chest pains and sudden numbness or weakness.

Anti-Seizure Medications

Drugs such as Phenytoin, Carbamazepine and Valproate are often prescribed to people suffering from epilepsy and other types of seizures. However, the same effect that causes muscles to relax and provide relief causes harm when individuals overdose on those pills. 

The Effects of Anti-Seizure Drug Overdose

Overdose on anti-seizure pills tends to cause arrhythmia and harm the central nervous system. This is evident from loss of muscle control, drowsiness and confusion. Additionally, the buildup of the active components in the liver may cause long-term damage, worsening the rest of the symptoms.


Almost every person consumes some form of stimulant, be it caffeine or nicotine. Here we refer to prescription stimulants used by individuals with ADHD or similar conditions. These are Adderall (Amphetamine) and Ritalin (Methylphenidate). We should also mention Cocaine since it’s commonly used by some as a strong stimulant and a “party drug”. Overdosing on these substances is potentially lethal or may cause severe brain and cardiovascular damage.

The Effects of Stimulant Overdose

Stimulant overdose primarily affects the cardiovascular system, leading to severe hypertension, fever and even cardiac arrest. Overstimulating the brain may lead to hallucinations or seizures. Watch out for unusually high agitation, chest pains, rapid heartbeat and high body temperature.


Benzodiazepines, or “benzos,” are used to treat insomnia, anxiety, and muscle spasms. Since their effects are mostly depressive and sedative, pill overdose makes normally beneficial effects harmful or even lethal. The most commonly prescribed benzos are Xanax (Alprazolam), Valium (Diazepam), Ativan (Lorazepam) and Klonopin (Clonazepam).

The Effects of Benzodiazepine Overdose

The sedative properties of benzos cause harmful effects when overdosing on these pills. Severe sedation may cause individuals to struggle to breathe or put them in a comatose state. The first signs of an overdose are extreme drowsiness, dizziness, loss of motion control and blurry vision.


Tricyclic antidepressants (Amitriptyline, Nortriptyline), SSRIs (Fluoxetine, Sertraline) and SNRIs (Venlafaxine, Duloxetine) are used both as prescribed and over-the-counter pills to help people suffering from anxiety and depression. In some cases, individuals try to mitigate the symptoms by ignoring the prescription and consuming more medication, leading to overdose.

The Effects of Antidepressant Overdose

The active components of antidepressants cause a number of harmful effects when overdosing on pills. The first one is increased heart rate and fever, the tell-tale signs of arrhythmia. It leads to respiratory issues as individuals find it hard to breathe. In this state, the brain is harmed, causing hallucinations and seizures.


Antipsychotic pills, such as Clozapine, Risperidone, Olanzapine and Haloperidol, are prescribed for a number of mental illness symptoms. Individuals using those medications tend to act impulsively and erratically. Without supervision, they may take more than they should, overdosing as a result. Antipsychotics affect the nervous and cardiovascular systems and, because of that, are particularly dangerous to mentally unstable individuals.

The Effects of Antipsychotics Overdose

The first sign of overdosing on antipsychotics is an irregular heartbeat. If left untreated, it may progress to more severe heart issues such as chronic arrhythmia. Affected individuals go into high fever and lose muscle control due to severe seizures. However, the most alarming symptom is an altered mental state due to changes in brain chemistry. Hallucinations may cause individuals to harm themselves or people around them.

Muscle Relaxants

This type of medication is often prescribed to people suffering from seizures or severe body injuries that hamper mobility. Baclofen, Cyclobenzaprine and Carisoprodol have saved thousands of lives and ensured a comfortable quality of life for many more. But it’s still possible to overdose on these pills, causing potentially lethal consequences.

The Effects of Muscle Relaxant Overdose

Overdosing on muscle relaxants causes strong confusion and dizziness, likely leading to physical trauma. Individuals often find it hard to breathe. In some cases, breathing stops entirely, requiring immediate medical attention. The sedative side effect may cause individuals to faint and become comatose. In this state, there is also a risk of long-term damage to the central nervous system.


Phenobarbital, Secobarbital, and Pentobarbital are sometimes used as sedatives and pain relief medications for intense chronic conditions such as migraines. Additionally, they have a muscle relaxant effect and can be used as anti-depressants. However, overdosing on barbiturate pills is extremely dangerous, evidenced by the fact that they are also used for euthanasia.

The Effects of Barbiturate Overdose

Barbiturates have a strong numbing effect, and during an overdose, it may cause respiratory failure as the muscles simply stop receiving signals to contract. The person becomes unresponsive and loses consciousness. If not treated immediately, the person becomes comatose and suffocates to death.

We hope you found this guide informative. Remember to be on the lookout for the symptoms of pill overdose and contact medical professionals at once unless you are trained in providing first aid. To prevent overdosing on drugs, we highly recommend following the prescription dosage or having another person help you maintain the regimen.

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