Key takeaways

  • Overdosing on antidepressants is possible with any type, though tricyclic antidepressants carry the highest risk of fatal outcomes compared to SSRIs, SNRIs, or MAOIs.
  • Symptoms of antidepressant overdose range from mild effects like drowsiness and nausea to severe complications, including seizures, irregular heartbeat, and serotonin syndrome, which occurs when excessive serotonin accumulates in the body.
  • It is best to seek emergency medical attention if overdose is suspected, even before severe symptoms appear, since some antidepressants may not cause serious symptoms for up to 24 hours after ingestion.

It’s possible to overdose on any type of antidepressant, especially if it’s taken with other drugs or medications.

Antidepressants are prescription medications used to treat the symptoms of depression, chronic pain, and other mood disorders. They work by increasing levels of certain chemicals in the brain, such as serotonin and dopamine.

There are several types of antidepressants available, including:

  • tricyclic antidepressants (TCAs), such as amitriptyline and imipramine (Tofranil)
  • monoamine oxidase inhibitors (MAOIs), like isocarboxazid (Marplan) and phenelzine (Nardil)
  • selective serotonin reuptake inhibitors (SSRIs), including fluoxetine (Prozac), sertraline (Zoloft), and escitalopram (Lexapro)
  • serotonin-norepinephrine reuptake inhibitors (SNRIs), such as duloxetine (Cymbalta) and venlafaxine (Effexor XR)
  • atypical antidepressants, including bupropion (Wellbutrin) and vortioxetine (Trintellix)

The lethal dosage of an antidepressant depends on many factors, including:

  • the type of antidepressant
  • how your body metabolizes the medication
  • your weight
  • your age
  • if you have any preexisting conditions, like a heart, kidney, or liver condition
  • if you took the antidepressant with alcohol or other drugs (including other antidepressants)

TCAs

When compared to other types of antidepressants, tricyclic antidepressants (TCAs) are among the most toxic in overdose.

Due to this toxicity, and the availability of safer alternatives, the use of TCAs has declined over the past 20 years. However, they’re still used to treat depression that hasn’t responded to other medications.

An older review of U.S. poison center data found that life threatening symptoms are typically seen with TCA doses greater than 1,000 mg. In one clinical trial, the lowest fatal dose of imipramine was just 200 mg.

The typical daily dose of the TCA amitriptyline is between 40 and 100 milligrams (mg). The typical dose of imipramine is between 75 and 150 mg per day.

The researchers recommended emergency treatment for anyone who’s taken a dose of desipramine, nortriptyline, or trimipramine greater than 2.5 mg per kilogram (kg) of weight. For a person who weighs 70 kg (about 154 pounds), this translates to about 175 mg.

For all other TCAs, emergency treatment is recommended for doses greater than 5 mg/kg. For a person who weighs 70 kg, this translates to about 350 mg.

SSRIs

Selective serotonin reuptake inhibitors (SSRIs) are the most commonly prescribed antidepressants because they tend to have fewer side effects. If taken alone, an SSRI overdose is rarely fatal.

The typical dosage of the SSRI fluoxetine (Prozac) is between 20 and 80 mg per day. A dose as low as 520 mg of fluoxetine has been associated with a lethal outcome, but there’s record of someone taking 8 grams (g) of fluoxetine and recovering.

The risk of toxicity and death is much higher when a high dose of an SSRI is taken with alcohol or other drugs.

SNRIs

Serotonin-norepinephrine reuptake inhibitors (SNRIs) are considered less toxic than TCAs, but more toxic than SSRIs.

A typical dose of the SNRI venlafaxine is between 75 and 225 mg per day, taken in two or three divided doses. Most reported cases of venlafaxine overdose occurred after taking doses several-fold higher than recommended doses. One patient experienced symptoms of overdose after taking a dose of 2.75 g.

Still, the majority of SNRI overdoses aren’t fatal, even at higher doses. Most cases of fatal overdoses involve more than one drug.

MAOIs

Monoamine oxidase inhibitors (MAOIs) are an older class of antidepressants and aren’t used as widely anymore. Most cases of MAOI toxicity happen when large doses are taken along with alcohol or other drugs.

Severe symptoms of an overdose can occur if you take more than 2 mg per kg of your body weight. Death from an MAOI overdose is rare, but this is likely because they aren’t widely prescribed anymore due to their many interactions.

Help is out there

If you or someone you know is in crisis and considering suicide or self-harm, please seek support:

  • Call or text the 988 Suicide and Crisis Lifeline at 988 or chat at 988lifeline.org. Caring counselors are available to listen and provide free and confidential support 24/7.
  • Text HOME to the Crisis Text Line at 741741 to connect with a volunteer crisis counselor for free and confidential support 24/7.
  • Not in the United States? Find a helpline in your country with Befrienders Worldwide.
  • Call 911 or your local emergency services number if you feel safe to do so.

If you’re calling on behalf of someone else, stay with them until help arrives. You may remove weapons or substances that can cause harm if you can do so safely.

If you’re not in the same household, stay on the phone with them until help arrives.

Overdosing on antidepressants can cause mild to severe symptoms. In some cases, death is possible.

Your individual symptoms will depend on:

  • how much of the medication you took
  • how sensitive you are to the medication
  • whether you took the medication in conjunction with other drugs

Mild symptoms

In mild cases, you may experience:

Severe symptoms

In severe cases, you may experience:

Serotonin syndrome

People who overdose on antidepressants may also experience serotonin syndrome. Serotonin syndrome is a serious negative drug reaction that occurs when too much serotonin builds up in your body.

Serotonin syndrome can cause:

Common antidepressant side effects

As with most medications, antidepressants can cause mild side effects even at a low dose. The most common side effects include:

The side effects may be uncomfortable at first, but they generally improve with time. If you experience these side effects while taking your prescribed dose, it doesn’t mean you’ve overdosed.

But you should still tell your doctor about any side effects you’re experiencing. Depending on your symptom severity, your doctor may want to reduce your dosage or switch you to a different medication.

If you suspect an overdose has occurred, seek emergency medical care right away. You should not wait until your symptoms get more severe. Certain types of antidepressants, especially MAOIs, may not cause severe symptoms for up to 24 hours after overdosing.

In the United States, you can contact the National Capital Poison Center at 800-222-1222 and await further instructions.

If symptoms become severe, call your local emergency services. Try to stay calm and keep your body cool while you wait for emergency personnel to arrive.

In the case of an overdose, emergency personnel will transport you to the hospital or emergency room.

You may be given activated charcoal while en route. This can help absorb the medication and alleviate some of your symptoms.

When you arrive at the hospital or emergency room, your doctor may pump your stomach to remove any remaining medication. If you’re agitated or hyperactive, they may use benzodiazepines to sedate you.

If you’re displaying symptoms of serotonin syndrome, they may also administer medication to block serotonin. Intravenous (IV) fluids may also be necessary to replenish essential nutrients and prevent dehydration.

Once your symptoms have subsided, you may be required to stay in the hospital for observation.

Once the excess medication is out of your system, you’ll most likely make a full recovery.

Antidepressants should only be taken under medical supervision. You should never take more than your prescribed dose, and you shouldn’t adjust this dose without your doctor’s approval.

Using antidepressants without a prescription or mixing them with other drugs can be extremely dangerous. You can never be sure of how it may interact with your individual body chemistry or any other medications or drugs you’re taking.

If you do choose to use antidepressants recreationally or mix them with other recreational substances, keep your doctor informed. They can help you understand your individual risk of interaction and overdose, as well as watch for any changes to your overall health.