Antidepressant Overdose

Overview

An antidepressant overdose happens when someone takes a larger amount of antidepressant medication than the body can safely process. This can occur accidentally, for example when doses are confused or a child finds pills, or intentionally as an act of self-harm. Antidepressants are among the most commonly prescribed medications, so overdoses are an important medical emergency.

How dangerous an overdose is depends largely on the type of antidepressant. Newer medicines such as SSRIs (selective serotonin reuptake inhibitors) and SNRIs are generally safer in overdose, though large amounts can still cause serious problems. Older tricyclic antidepressants (TCAs) are much more dangerous and can affect the heart and brain, sometimes fatally, even at relatively modest overdoses. Because the effects can worsen quickly and unpredictably, any suspected antidepressant overdose should be treated as an emergency. If self-harm is involved, compassionate, urgent help is essential.

If you or someone else may have taken too much medication, call emergency services or a poison control center right away. If someone is having thoughts of suicide or self-harm, reach out to a crisis or suicide helpline immediately.

Symptoms

Symptoms depend on the type and amount of medication and may appear within hours. They can range from mild to life-threatening and can worsen rapidly.

• Drowsiness, confusion, agitation, or trouble staying awake
• Fast, slow, or irregular heartbeat and palpitations
• Dizziness, low blood pressure, or fainting
• Nausea and vomiting
• Tremor, muscle twitching, or, in severe cases, seizures
• Dry mouth, blurred vision, and flushing (especially with tricyclics)
• High fever, rigid or jerking muscles, and severe agitation (a dangerous reaction called serotonin syndrome)

Tricyclic overdoses are particularly concerning because they can cause dangerous heart rhythm problems and seizures with little warning. Serotonin syndrome, which can occur from too much serotonin-related medication, is also a medical emergency.

Causes

An overdose results from taking more antidepressant than the body can handle.

• Intentional overdose: Taking too much medication as an act of self-harm; this requires both emergency medical care and mental health support.
• Accidental overdose: Confusing doses, taking medication too frequently, or a child accidentally swallowing pills.
• Drug interactions: Combining antidepressants with other medications, supplements, or substances that affect serotonin can cause serotonin syndrome even at usual doses.
• Mixing with alcohol or other drugs: This can increase sedation and danger.

Risk Factors

• Taking older tricyclic antidepressants, which are more toxic in overdose
• Depression or other mental health conditions, especially with thoughts of self-harm
• Access to large quantities of medication
• Combining multiple medications that affect serotonin
• Alcohol or substance use
• Young children in the home with unsecured medications

Diagnosis

In an emergency, evaluation happens quickly while treatment begins. Telling staff what was taken, how much, and when is very helpful.

• History: Identifying the medication, the amount, the timing, and any other substances involved.
• Vital signs and monitoring: Close monitoring of heart rate, blood pressure, breathing, and alertness.
• Electrocardiogram (ECG): Especially important with tricyclics to check for dangerous heart rhythm changes.
• Blood tests: To assess the body's chemistry and check for other substances; specific drug levels are useful for some medications.

Treatment

Treatment takes place in an emergency setting and is tailored to the medication and severity. There is no single antidote for most antidepressants, so care is largely supportive.

• Emergency stabilization: Supporting breathing, heart function, and blood pressure, and treating seizures if they occur.
• Heart rhythm treatment: For tricyclic overdoses, specific measures such as intravenous sodium bicarbonate may be used to protect the heart.
• Activated charcoal: Sometimes given soon after ingestion to reduce drug absorption, when appropriate.
• Treating serotonin syndrome: Cooling, sedation, fluids, and stopping the offending medication, with specific drugs in severe cases.
• Mental health support: When the overdose was intentional, psychiatric evaluation and ongoing support are an essential part of care.

Most people recover with prompt treatment, and the outlook is best when help is sought early.

Prevention

• Take antidepressants exactly as prescribed and keep track of doses
• Store medications safely, out of reach of children and others at risk
• Keep only the amount of medication you need on hand if self-harm is a concern
• Tell your doctor about all medicines and supplements to avoid interactions
• Seek help early for worsening depression or thoughts of self-harm
• Save the poison control number and emergency number where you can find them

When to See a Doctor

An antidepressant overdose is a medical emergency. Call emergency services immediately if someone has taken too much medication, especially if they are drowsy, confused, having seizures, having an irregular or racing heartbeat, or are difficult to wake. You can also contact a poison control center for guidance, but do not delay emergency care for serious symptoms. If a person is unconscious or not breathing, call emergency services and begin resuscitation if trained. If the overdose involved self-harm or someone is having thoughts of suicide, seek urgent help and contact a suicide or crisis helpline; this is a sign that compassionate, immediate support is needed.

Related Topics

Frequently Asked Questions

References

1. MedlinePlus, U.S. National Library of Medicine. Antidepressant overdose.
2. American Association of Poison Control Centers (Poison Help).
3. Mayo Clinic. Antidepressants and overdose.
4. Centers for Disease Control and Prevention (CDC).