The impacts of depression and anxiety can significantly affect your daily life.
Feelings of sadness, worry, worthlessness, low energy, and loss of interest in activities can make it difficult to work or enjoy time with friends and loved ones.
Untreated depression can make it difficult to accomplish simple, daily tasks.
A wide variety of safe and effective treatment options are available.
Antidepressants work to treat depression, anxiety, and other mental illnesses by affecting chemicals in the brain known as neurotransmitters.
There are five different classes of antidepressants: selective serotonin reuptake inhibitors (SSRIs), serotonin and norepinephrine reuptake inhibitors (SNRIs), monoamine oxidase inhibitors (MAOIs), tricyclic (TCAs), and atypical antidepressants.
Each works differently to target symptoms and each carries its own risks and side effects.
All antidepressants include the risk of overdose.
In this article, I’ll tell you more about antidepressant overdose.
I’ll talk about the proper dosing of different antidepressants, the symptoms of an overdose, and other substances that can interact with your antidepressant in a negative way.
I’ll also tell you want to do if you’re worried about an overdose.
Is Overdose on Antidepressants Possible?
Yes, it is possible to overdose when taking antidepressants.
The risk of overdose can increase depending on several factors, including other medications or drugs you may be taking.
Between the years 1999 and 2017, overdose deaths involving antidepressants more than tripled, from 1,749 to 5,269.
In 2019, the National Institute on Drug Abuse reported 5,174 fatalities driven by antidepressants, sometimes in combination with other drugs, including synthetic opioids and benzodiazepines.
Because antidepressants are only available through a prescription, your doctor or pharmacist will give you specific recommendations on how to take the medication.
To avoid an overdose, follow your doctor’s instructions and tell them about other medications you’re currently taking.
Proper and Lethal Doses of Antidepressants
The appropriate vs. the dangerous doses of antidepressants will vary depending on several factors, including your age, weight, medical history, type of antidepressant being used, and whether or not you are using or abusing other substances when taking the medication.
Selective serotonin reuptake inhibitors (SSRIs) are the first-line treatment prescribed for depression and anxiety.
They tend to cause fewer side effects and are less likely to cause problems at higher therapeutic doses than other types of antidepressants.
Common examples of SSRI medications include:
- Sertraline (Zoloft)
- Fluoxetine (Prozac)
- Paroxetine (Paxil)
- Fluvoxamine (Luvox)
- Citalopram (Celexa)
- Escitalopram (Lexapro)
- Vilazodone (Viibryd)
Doses of SSRI medication can range from 20-100 mg for tablets, or up to 20 mg per liter of liquid.
SSRIs are rarely fatal in overdose when taken alone.
The risk of toxicity can increase when SSRIs are taken with alcohol and other drugs.
Almost all deaths involving SSRIs involved additional substance use.
Serotonin and norepinephrine reuptake inhibitors (SNRIs) work by blocking the reabsorption of the neurotransmitters serotonin and norepinephrine in the brain.
In addition to treating depression, SNRIs can also be used to treat attention-deficit/hyperactivity disorder (ADHD).
Examples of SNRI medications include:
- Duloxetine (Cymbalta)
- Venlafaxine (Effexor)
- Desvenlafaxine (Pristiq)
- Levomilnacipran (Fetzima)
Like SSRIs, SNRIs are rarely fatal in overdose when taken alone.
They are less fatal in overdose than TCAs, but are slightly more fatal in overdose than SSRIs.
The relative toxicity for venlafaxine (dosage ranges between 37.5-225 mg per day) was five times higher than that for SSRIs.
At their lowest, overdoses of venlafaxine have been reported on dosages of 2 g (or 2,000 mg).
Tricyclic antidepressants (TCAs) are usually prescribed when SSRIs or SNRIs fail to improve symptoms.
TCAs can cause more side effects than SSRIs and SNRIs, and also have the highest case fatality and toxicity rate when compared with other antidepressants. TCA poisoning is fairly common in the US.
In part, TCAs’ potential for toxicity is due to their narrow range for therapeutic efficacy.
Therapeutic doses range from 20-150 mg, depending on the type of TCA being prescribed.
Adverse events have been recorded after just one additional dose, whether taken mistakenly or intentionally.
Examples of tricyclic antidepressants include:
- Imipramine (Tofranil)
- Nortriptyline (Pamelor)
- Dosulepin (Prothiaden)
- Desipramine (Norpramin)
Like TCAs, monoamine oxidase inhibitors (MAOIs) are usually prescribed when other classes of antidepressants have failed to resolve symptoms.
This is because MAOIs can cause serious side effects and must be accompanied by a strict diet, since interactions with some foods—including certain cheeses, pickles and wines—can be dangerous or even fatal.
MAOIs also cannot be combined with the use of SSRIs. For these reasons, MAOIs aren’t widely used.
Still, overdose is possible when taking more than 2 mg per kilogram of your body weight.
A kilogram is equal to 2.2 pounds.
Examples of MAOIs include:
- Tranylcypromine (Parnate)
- Phenelzine (Nardil)
- Isocarboxazid (Marplan)
Symptoms of Antidepressant Overdose
Symptoms of antidepressant overdose can range from mild to severe, depending on several factors.
If you’re experiencing moderate or severe symptoms, seek emergency care immediately.
Mild symptoms of an antidepressant overdose can include:
Severe symptoms of an antidepressant overdose can include:
- Rapid heartbeat
- Cardiac arrest
Serotonin syndrome is a rare, but serious condition that can occur when your brain has too much serotonin.
It can occur when you increase the dose of certain serotonin-increasing medications, or when you start a new medication.
Milder forms of serotonin syndrome can go away on their own after stopping the medication, but more severe forms may require emergency medical care.
Signs of serotonin syndrome can include:
- High fever
- Fast heart rate
- Muscle stiffness
- Loss of coordination
If you think you’re experiencing signs of serotonin syndrome, see your doctor right away or go to an emergency department.
Common Antidepressant Side Effects
Even when taken at the appropriate dose, antidepressants can cause side effects.
In many cases, these effects go away within the first few weeks of starting the medication.
But some side effects may persist. If you’re starting a new antidepressant, let your doctor know if and when new and bothersome side effects occur.
Some of the most common side effects of antidepressants include:
- Dry mouth
- Feeling restless
- Insomnia or trouble sleeping
- Sexual dysfunction
What to Do if You’re Worried About an Overdose
If you’re worried about an antidepressant overdose, seek medical attention immediately.
Not all overdoses are fatal, but it’s still crucial to get care as soon as possible.
How an Antidepressant Overdose May Be Treated
Depending on the severity of your overdose, you may be administered medication or intravenous (IV) fluids.
You will need close monitoring in an emergency department or hospital setting.
Antidepressants are a safe and effective treatment option for many mental health illnesses when taken as directed.
Still, there are risks and precautions to consider.
There are some safe antidepressant options to use during pregnancy (including sertraline), but others are not.
Tell your doctor if you’re pregnant or planning to become pregnant before starting antidepressants.
Tell your doctor if you’re breastfeeding before starting antidepressants, as some options may be safer than others.
Children and Young Adults
Some antidepressant medications may increase the risk of suicidal thoughts in children and young adults between the ages of 18-24.
Talk with your child’s doctor before starting medication to discuss a treatment and behavioral monitoring plan.
Alcohol use should be limited and in some cases avoided when taking antidepressants, as the combination can cause unwanted side effects.
Drinking alcohol while taking MAOIs can result in serious, heart-related side effects, including dangerously high blood pressure.
When taking SNRIs, consuming alcohol can cause a potentially fatal syndrome called rhabdomyolysis (RML).
RML can result in permanent disability and even death.
Using illegal drugs is not recommended when taking antidepressants, as the combination can cause unknown and potentially dangerous side effects.
Before starting a new medication, tell your doctor about all other medications you’re currently taking.
Certain kinds of antidepressants, like MAOIs, cannot be combined with other antidepressants.
Frequently Asked Questions
K Health articles are all written and reviewed by MDs, PhDs, NPs, or PharmDs and are for informational purposes only. This information does not constitute and should not be relied on for professional medical advice. Always talk to your doctor about the risks and benefits of any treatment.
K Health has strict sourcing guidelines and relies on peer-reviewed studies, academic research institutions, and medical associations. We avoid using tertiary references.
Monoamine Oxidase Inhibitor Toxicity. (2021).
Overdose Death Rates. (2021).
SSRI safety in overdose. (1998).
Toxicity of antidepressants: rates of suicide relative to prescribing and non-fatal overdose. (2010).
Tricyclic antidepressant poisoning: an evidence-based consensus guideline for out-of-hospital management. (2006).
Venlafaxine (Effexor) Summary of Basis for Regulatory Position. (2006).