Brain Injury After an Overdose: Signs, Symptoms and What Parents Can Do

    A Family’s Experience: When Something Feels Different After an Overdose

    A family shared to us that their son had survived several overdoses. Each time, they felt relief that he lived. But over time, they began to notice changes they couldn’t explain.

    He became more irritable. He forgot conversations. He struggled to follow through on simple plans. When they raised concerns, they were told it was “just the addiction.”

    What they didn’t realize—and what many families are never told—is that surviving an overdose can cause brain injury.

    A Hidden Problem

    An overdose is one of the most traumatic experiences a person can face. Too many families have experienced the loss of loved ones from fatal overdoses. But even a non-fatal overdose can have serious lasting consequences – like brain trauma.

    Additionally, individuals who suffer from a traumatic brain injury may be at increased risk of developing a substance use disorder.

    Brain injury after overdose has been called a “hidden epidemic” that people are often unaware of.1 In a PBS News documentary about overdose and brain trauma, a mother said of her son: “I always used to say that he would either turn around or he would die. There were two options. I never thought of the middle option of him actually overdosing but surviving with a brain injury.”2

    Educating yourself and your loved ones on the dangers of an overdose can help prevent them from happening, and understanding the complexities of a brain injury can help you and your loved ones heal.

    Key Takeaways

    1. Surviving an overdose can still injure the brain. Even a non-fatal overdose can reduce oxygen to the brain and cause lasting changes in memory, mood, behavior, and thinking. Repeated overdoses increase this risk.

    2. Brain injury can look like addiction or mental illness. Irritability, poor judgment, memory problems, and relapse may be caused by brain injury—not just substance use. Understanding this can change how families and providers respond.

    3. Reducing overdose risk protects both life and brain health. Harm reduction strategies like naloxone, not using alone, avoiding mixing substances, and using medications for opioid use disorder can help prevent overdose—and prevent brain injury.

    Substance Use and Traumatic Brain Injury: How They’re Connected

    An acquired brain injury (ABI) is an injury to the brain that happens after birth. It can be caused by an outside force, like a fall or car accident, or by a medical event, such as a stroke or overdose. Sometimes, more than one factor causes the injury.

    Brain injury is one of the most common disabilities in the United States. It can lead to long-term health problems and a higher risk of early death.3

    Research suggests that people who experience a traumatic brain injury (TBI)—especially during childhood or the teen years—may be more likely to develop a substance use disorder later in life.4 This higher risk may be linked to:5

    • Being prescribed opioids for pain
    • Trouble getting ongoing medical or mental health care
    • Changes in brain chemistry that affect judgment
    • Using substances to cope with pain or stress
    • A history of substance use before the injury

    Substance use can also increase the risk of accidents that cause brain injuries. One study found that nearly 47% of people hospitalized with a traumatic brain injury had substances in their system at the time of injury.6

    How Overdose Can Cause Brain Injury

    Nonfatal overdoses—especially those involving opioids—can cause brain injury when the brain does not get enough oxygen. During an overdose, breathing may slow down or stop. This is called respiratory depression. When this happens, oxygen cannot reach the brain, and brain damage can begin in just a few minutes.7

    Today’s drug supply increases this risk. Powerful substances like fentanyl and xylazine can slow breathing very quickly and for longer periods of time, raising the chance of overdose-related brain injury.8

    Brain injury caused by overdose or toxic substances is often called toxic brain injury or neurotoxicity, rather than traumatic brain injury.9 This type of injury may be:

    • Hypoxic – when the brain gets too little oxygen
    • Anoxic – when the brain gets no oxygen at all

    Why Repeated Overdoses Increase Brain Damage Risk

    Many families don’t realize that repeated nonfatal overdoses can slowly damage the brain. Even if someone survives multiple overdose, repeated loss of oxygen puts ongoing stress on brain cells.

    Over time, this can lead to:

    • Memory problems
    • Trouble focusing or thinking clearly
    • Poor judgment and impulsive behavior
    • Difficulty controlling emotions
    • A higher risk of seizures

    These changes may happen slowly and are often mistaken for continued substance use or mental health disorders.

    Signs and Symptoms of Brain Injury After Overdose

    Short-term symptoms of toxic brain injuries may include:10

    • Difficulty with coordination and balance
    • Trouble concentrating and confusion
    • Dizziness and feeling lightheaded
    • Headache
    • Fatigue
    • Changes in mood

    More severe, long-lasting symptoms include:

    • Difficulty regulating mood and emotions
    • Muscle spasms and reduced motor function
    • Issues with short-and long-term memory
    • Speech impairments
    • Vision problems
    • Cognitive decline
    • Increased aggression

    Why Brain Injury Can Look Like Addiction or Mental Illness

    Brain injuries often affect the parts of the brain that control judgment, emotions, and self-control. Because of this, a person may:

    • Have trouble following rules or treatment plans
    • Seem unmotivated or disconnected
    • Have emotional outbursts or anger
    • Deny problems that seem obvious to others
    • Relapse more easily

    For families, this can be confusing and painful. These behaviors may be caused by changes in the brain, not a lack of effort or caring.

    How Brain Injuries Are Diagnosed and Treated

    Treatment depends on how severe the injury is, the person’s symptoms, and whether they have had previous brain injuries or behavioral health conditions.

    • Mild brain injuries are often treated with rest, monitoring, and pain relief.
    • More serious brain injuries usually require hospital care and sometimes surgery, followed by rehabilitation.

    Rehabilitation may involve several specialists, including:

    • Neurologists
    • Physical therapists
    • Speech and language therapists
    • Mental health professionals

    The Substance Abuse and Mental Health Services Administration (SAMHSA) recommends treating brain injuries in a whole-person way, including support for mental health and substance use disorders.11

    It’s important to know that brain injuries can be hard to diagnose. Mild brain injuries do not always show up on scans, and symptoms may appear days or weeks later. About 75% of traumatic brain injuries are considered mild.12 This means that sometimes, someone with a brain injury might present with no or very light symptoms.

    Getting the Right Evaluation

    If your loved one has survived an overdose and continues to have changes in memory, mood, or behavior, further evaluation may help. This can include:

    • A visit with a neurologist
    • Neuropsychological testing
    • Screening for seizures
    • Substance use treatment that understands brain injury

    Keeping track of overdoses, head injuries, and hospital visits can help healthcare providers see the full picture.

    Brain injuries can affect a person’s ability to:

    • Learn new information
    • Keep a job
    • Follow court or probation rules
    • Manage daily responsibilities

    Some people may need accommodations, job training, or disability services. Families often need to explain how brain injury affects their loved one’s behavior and functioning.

    How Parents Can Reduce Overdose Risk and Protect Brain Health

    Many people don’t realize that surviving an overdose can result in brain damage. Helping your loved one reduce the risks of their substance use can prevent an overdose from happening in the first place. Some strategies include:

    Support for Parents and Caregivers

    Caring for someone who has survived an overdose—and may have a brain injury—can be exhausting and heartbreaking. Many parents grieve about the changes they see while still hoping their loved one can heal.

    You are not alone. Support is available.

    If you’re worried about your loved one’s substance use or changes after an overdose and don’t know where to turn, please reach out to us. You may also need help to process your own emotions, especially if you witnessed your child’s overdose. Our trained and compassionate Helpline Specialists will listen to your concerns and help you think through next steps. Click here to connect with us.

    1 Brain injury after overdose is a hidden epidemic: Recognizing and treating the survivors of the toxic drug crisis
    2 Roads to Recovery | Overdose and Brain Injury (PBS) ; Neurotoxicity (Cleveland Clinic)
    3 Neurotoxicity (Cleveland Clinic) ; Hypoxic/Anoxic Brain Injury (Brain Injury Association of America)
    3 Traumatic Brain Injury & Concussion (CDC)
    4 Cannella, L. A., McGary, H., & Ramirez, S. H. (2019). Brain interrupted: Early life traumatic brain injury and addiction vulnerability. Experimental neurology, 317, 191–201. https://doi.org/10.1016/j.expneurol.2019.03.003
    5 Olsen, C. M., & Corrigan, J. D. (2022). Does Traumatic Brain Injury Cause Risky Substance Use or Substance Use Disorder?. Biological psychiatry, 91(5), 421–437. https://doi.org/10.1016/j.biopsych.2021.07.013
    6 Andelic, N., Jerstad, T., Sigurdardottir, S., Schanke, A. K., Sandvik, L., & Roe, C. (2010). Effects of acute substance use and pre-injury substance abuse on traumatic brain injury severity in adults admitted to a trauma centre. Journal of trauma management & outcomes, 4, 6. https://doi.org/10.1186/1752-2897-4-6
    7 Respiratory Depression (Hypoventilation)
    8 Todaro, D. R., Volkow, N. D., Langleben, D. D., Shi, Z., & Wiers, C. E. (2024). Collateral Damage: Neurological Correlates of Non-Fatal Overdose in the Era of Fentanyl-Xylazine. Neuroscience insights, 19, 26331055241247156. https://doi.org/10.1177/26331055241247156
    9 Hypoxic and anoxic brain injury (Headway)
    10 Winstanley, E. L., Mahoney, J. J., 3rd, Castillo, F., & Comer, S. D. (2021). Neurocognitive impairments and brain abnormalities resulting from opioid-related overdoses: A systematic review. Drug and alcohol dependence, 226, 108838. https://doi.org/10.1016/j.drugalcdep.2021.108838
    11 Treating Patients with Traumatic Brain Injury | SAMHSA
    12 Harris K, Brusnahan A, Shugar S, Miner J. Defining Mild Traumatic Brain Injury: From Research Definition to Clinical Practice. J Surg Res. 2024 Jun;298:101-107. doi: 10.1016/j.jss.2024.03.006. Epub 2024 Apr 8. PMID: 38593600.