What Happens if I Accidentally Take My Antidepressant Twice?

For most adults, accidentally taking a second dose of their antidepressant on the same day causes uncomfortable but temporary side effects rather than a medical emergency. You might feel nauseous, dizzy, or jittery for several hours. That said, the severity depends heavily on which antidepressant you take, what dose you’re on, and whether you’re also on other medications that affect the same brain chemicals. Some drug classes carry specific risks at double-dose levels that are worth knowing about before you decide whether to just ride it out or call your doctor.

The Most Common Side Effects of a Double Dose

The symptoms you’re most likely to notice after accidentally doubling up are gastrointestinal. Nausea tops the list, and it’s not random. When you take a serotonin-boosting antidepressant like an SSRI or SNRI, the extra serotonin floating around your gut activates receptors on nerve fibers that send signals to your brain’s vomiting center. That same surge of serotonin speeds up your intestinal contractions and increases fluid secretion, which can translate to diarrhea or loose stools.¹ These effects usually peak within a few hours and fade as your body processes the extra medication.

Beyond the gut, expect amplified versions of whatever side effects you experienced when you first started the medication. If your antidepressant made you drowsy initially, a double dose may make you noticeably sleepy. If it tended to make you feel wired or restless, you’ll probably feel more of that. Headache, dry mouth, increased sweating, and mild tremor are all in play. For most people, these symptoms are self-limiting and resolve within a day.

Why the Specific Drug Matters a Lot

Not all antidepressants carry the same risks at double-dose levels. A large review of accidental double-dose ingestions reported to the nation’s largest poison control system found that behavior-modulating medications (a category that includes antidepressants) accounted for over a third of all moderate and major effects. Among the specific drugs linked to the most serious outcomes were bupropion, beta blockers, calcium channel blockers, propafenone, and tramadol.² That bupropion made this list while most SSRIs did not tells you something about relative risk.

SSRIs

Selective serotonin reuptake inhibitors like sertraline, fluoxetine, escitalopram, and paroxetine generally have wide therapeutic margins, meaning the gap between your prescribed dose and a dangerous amount is relatively large. A single accidental double dose of most SSRIs in a healthy adult is unlikely to cause anything beyond the amplified side effects described above. The exception worth flagging is citalopram. Research has found that citalopram produces a dose-dependent increase in a heart rhythm measurement called the QTc interval, with the effect becoming more pronounced at doses of 30 mg or higher.³ A prolonged QTc interval can, in rare cases, trigger a dangerous heart rhythm called torsades de pointes, though this has primarily been reported in overdose situations or in people who already had abnormal electrolytes, kidney problems, or liver problems.⁴ If you’re on a higher dose of citalopram and accidentally double it, that’s a situation worth a call to your doctor or pharmacist, especially if you have any existing heart conditions.

SNRIs

Serotonin-norepinephrine reuptake inhibitors like venlafaxine and duloxetine affect two neurotransmitter systems rather than one, which adds a layer of concern. The norepinephrine component can bump up your blood pressure and heart rate. Venlafaxine is the one to watch here. Blood pressure elevation is a recognized effect at higher doses, but case reports have documented accelerated hypertension even at relatively standard doses. One report described a patient whose diastolic blood pressure surged above 120 mmHg on just 150 mg per day, well below the 300 mg threshold where blood pressure problems are most commonly expected.⁵ If you accidentally double your venlafaxine dose and notice a pounding headache, chest tightness, or blurred vision, check your blood pressure if you can and contact your prescriber.

Bupropion

Bupropion (Wellbutrin) stands apart from serotonin-based antidepressants because it works primarily on dopamine and norepinephrine. It also has a narrower safety margin. After a bupropion overdose, the primary clinical effects show up in the nervous system and can include tremor, confusion, agitation, hallucinations, and seizures.⁶ A single accidental double dose in an adult isn’t the same as an intentional overdose, but bupropion’s seizure risk is dose-related, and it was specifically named among the medications causing major outcomes in the double-dose poison control review.² If you’re on a higher daily dose and accidentally double it, err on the side of calling Poison Control or your prescriber rather than waiting to see what happens.

Tricyclic and Older Antidepressants

Tricyclic antidepressants like amitriptyline, nortriptyline, and imipramine have the narrowest therapeutic margins of any commonly prescribed antidepressant class. Even moderate overdoses can cause cardiac conduction abnormalities, seizures, and dangerous drops in blood pressure. If you accidentally take a double dose of a tricyclic, calling your doctor or a poison control center is reasonable regardless of how you feel in the moment, because cardiac effects can develop with a delay.

When Serotonin Syndrome Enters the Picture

Serotonin syndrome is the complication people worry about most when they realize they’ve taken extra antidepressant. The reassuring reality is that most cases of serotonin toxicity involve two different drugs that increase serotonin through different mechanisms, not simply a higher-than-usual dose of one drug. The most dangerous combination is a monoamine oxidase inhibitor taken alongside an SSRI or SNRI.⁷ A single accidental double dose of one SSRI, taken alone, is very unlikely to trigger full-blown serotonin syndrome in most people.

That doesn’t mean you should dismiss the possibility entirely, especially if you’re taking other medications or supplements that also boost serotonin. Triptans for migraines, the pain medication tramadol, certain herbal supplements like St. John’s wort, and even the cough suppressant dextromethorphan all raise serotonin levels to varying degrees. If you accidentally double your antidepressant and you’re also taking something from that list, the combined serotonin load could push things into dangerous territory.

The symptoms to watch for are specific and recognizable. Clinicians use a set of diagnostic criteria that center on a handful of key signs: jerky, involuntary muscle movements (called clonus), agitation, heavy sweating, tremor, and exaggerated reflexes. In life-threatening cases, severe muscle rigidity and a temperature above 38°C (about 100.4°F) are consistently present.⁸ Ordinary side effects from a double dose, like nausea or mild jitteriness, are not the same thing. If you notice rhythmic twitching in your ankles or wrists, uncontrollable shivering, profuse sweating paired with agitation, or a rapid climb in body temperature, seek emergency care.

What To Do Right After You Realize

The moment you realize you’ve doubled up, take a breath. For the majority of antidepressants at the majority of prescribed doses, one extra dose is going to make you uncomfortable, not put you in the hospital. Here’s a practical framework:

Skip the next dose: Don’t try to “make up” for the extra by skipping two doses later. Just skip the one that immediately follows and then resume your normal schedule. This lets your blood levels come back into range without creating a withdrawal gap.
Call Poison Control: In the U.S., the number is 1-800-222-1222 and it’s staffed 24 hours a day. The specialists there can look up your specific medication and dose, account for your other medications, and tell you whether you need medical attention or just monitoring. This is exactly what they’re trained for.
Watch for escalating symptoms: Mild nausea, drowsiness, or a headache that peaks and fades is expected. Symptoms that keep getting worse over several hours, particularly rapid heartbeat, chest pain, confusion, involuntary muscle movements, or a high temperature, warrant a trip to the emergency department.
Stay hydrated: If you’re dealing with nausea or diarrhea, keep sipping water or an electrolyte drink. The GI effects of a double dose are self-limiting but can leave you dehydrated.

Don’t induce vomiting. It’s rarely recommended for accidental double-dose situations and can cause its own complications. If the dose was taken more than an hour or two ago, much of the medication has already been absorbed anyway.

Why Some People Are More Sensitive Than Others

Two people on the same antidepressant at the same dose can have very different reactions to an accidental doubling, and genetics is a big part of why. One liver enzyme in particular, called CYP2D6, is responsible for breaking down roughly 20 to 25 percent of all medications, including many antidepressants. The gene that codes for this enzyme is highly variable across the population. Some people carry versions that make the enzyme work faster than normal, meaning they clear drugs quickly. Others carry versions that produce a sluggish or nonfunctional enzyme, meaning the drug lingers in their system longer and reaches higher blood levels even at standard doses.⁹

If you’re someone who metabolizes antidepressants slowly, an accidental double dose effectively hits your system harder than it would hit a fast metabolizer. You may not know your metabolizer status unless you’ve had pharmacogenomic testing, but you might have clues from your history. If you’ve always been unusually sensitive to medication side effects, or if your doctor has had to prescribe you lower-than-typical doses for things to work, slow metabolism could be part of the picture.

Beyond genetics, certain drugs can temporarily slow down CYP2D6 even in people who are genetically normal metabolizers. This is called phenoconversion: the drug is essentially converting you into a poor metabolizer for as long as you’re taking it. Common culprits include the antihistamine diphenhydramine (Benadryl), the antidepressant paroxetine (which inhibits the very enzyme that’s supposed to break it down), and the antifungal terbinafine.⁹ If you’re taking one of these alongside your antidepressant, an accidental double dose could produce stronger effects than you’d otherwise expect.

Children and Accidental Ingestion

The conversation changes significantly when a child accidentally swallows an adult’s antidepressant, even a single dose. A medication dose calibrated for a 70 kg adult can be dramatically disproportionate to a toddler’s body weight. One case report described a three-year-old who ingested an estimated 2 grams of bupropion, resulting in seizures that progressed to dangerously low blood pressure and a slow heart rate requiring full resuscitation efforts.¹⁰ While earlier reports had suggested bupropion ingestion in children caused few effects beyond seizures, this case demonstrated that cardiovascular collapse is possible.

If you have small children in the home and you take antidepressants, standard childproofing applies: medication in child-resistant containers, stored out of reach and out of sight, never left loose on countertops or in open pill organizers. If a child ingests any amount of an adult’s antidepressant, call Poison Control or go to an emergency department regardless of whether the child appears symptomatic. Unlike adults, who can often safely wait and observe after a double dose, children need professional assessment promptly.

Preventing Repeat Mistakes

Accidentally doubling a dose usually isn’t a character flaw. It’s a predictable result of taking medication on autopilot, especially if you take it at a time of day when your attention is divided. The “did I already take that?” moment is so common that it basically happens to everyone who takes daily medication over a long enough period.

A few strategies that actually help: pill organizers with labeled compartments for each day of the week give you a visual check. If the Wednesday compartment is empty, you took it. Smartphone alarm apps that require you to confirm the dose with a tap create a record you can look back at. If you’re someone who often forgets whether you took your morning dose, moving your dose to a more distinctive moment in your routine, like right after brushing your teeth at night, can anchor it to a behavior that’s harder to forget.

Some people put their pill bottle upside down after taking their morning dose, then flip it right-side up at bedtime as a reset. It’s low-tech, but it works for plenty of people precisely because it creates a physical cue you can check without having to rely on memory. The goal isn’t a perfect system. It’s a system that answers the “wait, did I already take that?” question before you swallow a second pill.

Extended-Release Formulations and Timing

If you take an extended-release (ER or XR) version of your antidepressant, a double dose deserves slightly more attention than the same mistake with an immediate-release tablet. Extended-release formulations are designed to deliver medication gradually over many hours. Doubling one means you’ve loaded your body with a slow-release reservoir that will keep pushing out more drug than intended for an extended period, potentially 12 to 24 hours depending on the formulation. You can’t “undo” it by skipping a later dose in the way that works reasonably well with immediate-release drugs, because the extra medication is already sitting in your gut being absorbed on a timer.

Bupropion XL is a good example of why this matters. The extended-release version was developed specifically to keep blood levels more stable and reduce the seizure risk associated with the immediate-release version’s peak-and-trough pattern. Doubling the XL version defeats that purpose by creating a prolonged period of elevated blood levels. The same logic applies to venlafaxine XR and desvenlafaxine ER. If you’ve doubled an extended-release antidepressant, Poison Control can give you guidance specific to the formulation, and that call is worth making even if you feel fine in the first hour or two.

One more timing nuance: if you normally take your antidepressant in the morning and you can’t remember whether you took it, and it’s now mid-afternoon, it’s generally better to skip the uncertain dose entirely and take tomorrow’s as scheduled. The brief interruption from missing one dose is almost always less risky than the potential consequences of doubling up, especially for medications with narrower safety margins. Your next dose is never more than a day away, and one missed dose of most antidepressants won’t trigger meaningful withdrawal symptoms.

1
Psychopharmacology Institute. What Happens if I Accidentally Take My Antidepressant Twice? – Section: Mechanisms of Antidepressant-Induced GI Side Effects
2
PubMed. A 10-year review of single medication double-dose ingestions in the nation’s largest poison control system
3
PubMed Central. Evaluation of QTc prolongation and dosage effect with citalopram
4
PubMed Central. Prolonged QTc interval and torsades de pointes induced by citalopram
5
PubMed Central. Accelerated hypertension after venlafaxine usage
6
PubMed Central. Seizures after overdoses of bupropion intake
7
PubMed Central. Demystifying serotonin syndrome (or serotonin toxicity)
8
PubMed. The Hunter Serotonin Toxicity Criteria: simple and accurate diagnostic decision rules for serotonin toxicity
9
PubMed Central. CYP2D6 pharmacogenetics and phenoconversion in personalized medicine
10
PubMed Central. Cardiotoxicity associated with accidental bupropion ingestion in a child