Antidepressants can improve the symptoms of depression, but, like all medications, they can also have side effects. The vast majority of people who take antidepressants experience at least one side effect. Most of them are minor and usually subside on their own over time. Particularly bothersome side effects can be treated with medication or by dose reduction, changing the administration time, or switching to a different antidepressant.
Evidence indicates that antidepressants should be taken with caution, with full awareness of the risks, and close attention to side effects. That said, antidepressants have been used safely by millions of people for more than 20 years.
Side effects that are characteristic of most, if not all, antidepressants include:
Gastrointestinal disturbances: Nausea and diarrhea are dose-related and usually resolve within the first two weeks of treatment with antidepressants. Starting medications at low doses or taking them with food can reduce nausea and diarrhea.
Weight gain: Since depression is often associated with appetite suppression and weight loss, weight gain during antidepressant treatment can either be a sign of symptom improvement or a side effect of antidepressants. Weight gain can occur with nearly all antidepressants, due in part to enhanced appetite and carbohydrate craving.
Generally speaking, some antidepressants seem more likely to cause weight gain than others. For instance, the tricyclic antidepressants (TCAs) and perhaps monoamine oxidase inhibitors (MAOIs) may be more likely to cause weight gain than the selective serotonin reuptake inhibitors (SSRIs) or the newer antidepressants, with the exception of Remeron. SSRIs tend to cause loss of appetite early on, sometimes due to side effects like nausea, and others can cause weight gain with long-term use (e.g., Paxil). Some antidepressants, like Effexor and Wellbutrin, may be less likely to cause any weight gain.
The extent of weight gain largely depends on the specific drug, the dosage, and the duration of treatment. Prevention is the ideal strategy to cope with weight gain and typically involves healthy eating habits and physical activity.
Sleep disturbances: Either insomnia or drowsiness can be managed with other medications or changes in dose or administration time of antidepressants. Nightmares and vivid dreams have also been reported in some patients, but these side effects often go away within a few weeks and rarely lead to a change in medication.
Sexual dysfunction: Sexual dysfunction is a reversible side effect, usually characterized by delayed ejaculation, decreased libido, or anorgasmia (inability to achieve an orgasm), which occurs in both men and women taking antidepressants. This may be addressed by reducing the dosage, switching to another agent, or adding another drug to overcome the sexual side effects. It is important to remember that mental illnesses in themselves can affect sexual desire and performance.
Serotonin syndrome: Serotonin syndrome is a rare but serious drug reaction that occurs when two serotoninergic (drugs that increase serotonin in the brain) medications are taken at the same time. It is characterized by nausea, diarrhea, restlessness, extreme agitation, muscle twitches, hyperthermia, rigidity, delirium, and seizure.
Antidepressant discontinuation syndrome (withdrawal): With abrupt discontinuation of these medications, patients may experience dizziness, nausea, weakness, insomnia, anxiety, irritability, and headache. These symptoms tend to go away within a week. Tapering antidepressants should help to avoid discontinuation syndrome.
Suicidal thoughts or actions: Antidepressant medicines may increase suicidal thoughts or actions in some children, teenagers, and young adults when the medicine is first started. Depression and other mental illnesses are the most important causes of suicidal thoughts and actions.
Side Effects of Different Antidepressant Types
Monoamine Oxidase Inhibitors: MAOIs are associated with daytime sedation, dizziness, orthostatic hypotension (postural blood pressure changes), dry mouth, nervousness, muscle aches, paresthesia (tingling sensation), insomnia, weight gain, sexual dysfunction, and urinary difficulty.
Tricyclic Antidepressants: Tricyclic antidepressants generally have more side effects than other antidepressants, including headaches, sleepiness, significant weight gain, nervousness, dry mouth, constipation, bladder problems, sexual problems, blurred vision, dizziness, drowsiness, skin rash and heart conduction changes.
Selective Serotonin Reuptake Inhibitors: SSRIs are generally well tolerated overall. Transient side effects of SSRIs include nausea, vomiting, diarrhea, headache, fatigue, nervousness, and dry mouth. Some of the more persistent, or chronic, side effects are daytime fatigue, insomnia, sexual problems and weight gain.
Serotonin-Norepinephrine Reuptake Inhibitors: SNRIs have similar side effects to the SSRIs. The most common side effects of these antidepressants include nausea, dizziness, insomnia, somnolence, dry mouth, and sexual dysfunction. SNRIs may increase blood pressure, especially at high doses.
Side Effects of Atypical Antidepressants
- Desyrel commonly causes sedation, dizziness, orthostatic hypotension, dry mouth, nausea, and headache.
- Wellbutrin commonly causes insomnia, headache, and restlessness. Increased irritability and agitation may also occur. Wellbutrin has the lowest risk of sexual side effects, fatigue and weight gain of all antidepressants. Higher doses of Wellbutrin have been linked to seizures.
- Remeron commonly causes fatigue, dizziness, transient sedation, and weight gain. It is less likely to cause insomnia, sexual side effects, and nausea.
People respond to antidepressants differently and it is not uncommon to try several before you find the one that works best. Monitor and keep track of any side effects that you experience. Contact your doctor regarding bothersome side effects or if your depression gets worse. Managing your side effects may improve the success of antidepressant therapy.