Why Do I Feel Sick When I Miss a Dose of My Antidepressant?

Missed Antidepressant Dose
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Like many people, you've probably taken your antidepressant late a few times, or even forgotten to take it altogether for a day or two. If you sometimes feel like you have the flu with an upset stomach, achiness, and dizziness when this happens, you may be experiencing what's known as discontinuation syndrome.

Discontinuation syndrome refers to a range of symptoms that can occur if a person suddenly stops taking or changes their dose of an antidepressant medication.

Symptoms of discontinuation syndrome can happen when you significantly lower your dose or suddenly stop taking any type of antidepressant. But, they're more likely to happen with certain antidepressants.

Symptoms of Discontinuation Syndrome

Missing a dose of Zoloft or another antidepressant may be enough to trigger symptoms of discontinuation syndrome in some people. For many people, discontinuation syndrome symptoms may be quite mild, but others may find them particularly difficult to cope with. Here's an overview of the most common symptoms.

  • Agitation
  • Anxiety
  • Blurred vision
  • Chills
  • Dizziness
  • Fatigue
  • Headache
  • Insomnia
  • Irritability
  • Muscle pain
  • Nausea
  • Runny nose
  • Sweating
  • Tingling sensations
  • Tremor
  • Vivid dreams

Less common symptoms are:

  • Electric shock sensations
  • Hallucinations
  • Hypertension
  • Lack of coordination

Causes of Discontinuation Syndrome

There are several different causes of discontinuation syndrome. Here is an overview of the most common causes for your symptoms.

  • Suddenly stopping your antidepressant: If you've been taking an antidepressant for a month or more and you suddenly quit taking it, you're far more likely to have discontinuation symptoms than if you had tapered off slowly. It may take one to four days before you notice symptoms. For example, missing a Lexapro dose (or a few doses) might cause you to begin experiencing symptoms over the next few days.
  • Tapering off of your antidepressant too quickly: Especially if you've been taking a high dose or you've been on an antidepressant for an extended period of time, a slow and gradual tapering schedule is necessary to prevent discontinuation symptoms.
  • Missing or skipping a dose or two of your antidepressant: It's estimated that up to 70% of people who take antidepressants skip doses here and there. However, doing this increases your risk of developing discontinuation symptoms, especially if you're taking an antidepressant with a short half-life. These types are eliminated from your body so rapidly that discontinuation symptoms may appear fairly soon after a missed dose, sometimes within hours.
  • Switching to a different formulation: Though this isn't common, if you're going from a brand name antidepressant to a generic or from one generic to another made by a different company, the formulation may be different enough that you experience discontinuation symptoms.

Suddenly discontinuing or significantly and quickly lowering your dose of any type of antidepressant puts you at risk for discontinuation symptoms.

The most common culprit seems to be immediate-release Effexor (venlafaxine) because it has a half-life as short as three to five hours, and it's also the most likely antidepressant to cause these symptoms when you miss a dose or take it late.

Other more common culprits of discontinuation syndrome include Paxil (paroxetine), Pristiq (desvenlafaxine), Zoloft (sertraline), Elavil (amitriptyline), Tofranil (imipramine), and all monoamine oxidase inhibitors (MAOIs).

Treatment for Discontinuation Syndrome

Treatment for discontinuation syndrome may involve restarting the medication and then slowly tapering. In some cases, however, people may be unwilling or unable to restart the medication, particularly if they experienced severe or significant side effects. 

Discontinue syndrome is less frequent and severe when taking Prozac (fluoxetine), so your doctor may recommend switching to that drug before you stop taking your medication.

Research also suggests that cognitive behavioral therapy (CBT) can help people cope with feelings of distress they may experience.

If restarting and tapering the medication is not an option, withdrawal symptoms will typically resolve within one to two weeks. The most severe symptoms often begin to improve within one to three days. During this time, supportive self-care can help people manage symptoms until they recover.

Prevention of Discontinuation Syndrome.

So how can you prevent discontinuation symptoms from happening? First, if you do miss a dose of your antidepressant, go ahead and take it as soon as you remember, unless it's close to time for your next dose. In that case, don't double up; just skip the missed dose and take your next dose as usual.

Here are some other ways to prevent discontinuation syndrome.

Take Medicine on Time

The best way to avoid having these symptoms is to be very careful with properly timing your medication dose. Taking your medication as prescribed also makes it as effective as possible in treating your depression symptoms.

One good way to make sure you take your medicine at the right time is to set alarms in your calendar or clock on your smartphone or computer.

If you're not a techie, consider using an old-fashioned alarm clock, writing yourself notes, leaving your medicine out where you can see it, setting an alarm on your watch, and/or getting a pill box for each day of the week.

Think About Switching

If you're finding taking your medication on time difficult to manage, consider asking your doctor about trying a different antidepressant with a longer half-life or an extended-release formula so you don't have to take it as often. 

For instance, Prozac (fluoxetine) has a half-life of four to six days, so it takes longer to completely clear out of your body than other antidepressants. This means that the likelihood of having discontinuation symptoms if you miss a dose is pretty low.

Missing a dose of Prozac would result in fewer symptoms than missing a dose of Zoloft or Effexor.

Talk to Your Doctor Before Stopping

If you ever need to stop taking your antidepressant altogether, you should always consult with your doctor first. 

Don't ever stop your antidepressant without your doctor's knowledge.

Depending on what you're taking, how long you've been taking it, and the dosage, they can help you avoid discontinuation syndrome by creating a plan to gradually and slowly taper you off your medication if needed.

A Word From Verywell

Discontinuation syndrome is quite common, occurring in an estimated 20% to 33% of people who have taken antidepressants. Although many experts refer to this phenomenon as withdrawal, experiencing antidepressant discontinuation syndrome doesn't mean that you're addicted. 

Antidepressants are rarely habit forming and don't create the cravings, euphoric effects, tolerance, or drug-seeking behavior that are all seen with drugs of abuse. Another difference is that symptoms of discontinuation syndrome are generally milder and last for less time than symptoms of illicit drug withdrawal.

Rest assured that if you do experience these symptoms, they generally tend to be mild, usually go away within one to two weeks, and are easily treatable if they do become moderate or severe. Stay in close contact with your doctor if you're discontinuing your antidepressant so he or she can minimize any discontinuation symptoms you may have.

4 Sources
Verywell Mind uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Gabriel M, Sharma V. Antidepressant discontinuation syndrome. CMAJ. 2017;189(21):E747. doi: 10.1503/cmaj.160991

  2. Bhat V, Kennedy SH. Recognition and management of antidepressant discontinuation syndrome. J Psychiatry Neurosci. 2017;42(4):E7-E8. doi: 10.1503/jpn.170022

  3. Warner CH, Bobo W, Warner C, Reid S, Rachal J. Antidepressant discontinuation syndrome. Am Fam Physician. 2006;74(3):449-56.

  4. Wilson E, Lader M. A review of the management of antidepressant discontinuation symptoms. Ther Adv Psychopharmacol. 2015;5(6):357-68. doi: 10.1177/2045125315612334

Additional Reading

By Nancy Schimelpfening
Nancy Schimelpfening, MS is the administrator for the non-profit depression support group Depression Sanctuary. Nancy has a lifetime of experience with depression, experiencing firsthand how devastating this illness can be.