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Antidepressants Medications Side Effects


All antidepressants cause unwanted effects. The most common problems are nausea, sexual problems, weight gain, sleepiness, trouble sleeping, dry mouth, constipation. Moreover, these medications can be dangerous under certain conditions.

You may experience some or none of the side effects. Unfortunately, there is no way to know beforehand if you will have side effects from a medication that you have never tried.

Different antidepressants have different risks. Here we have summarised the most frequent side effects that people experience during treatment with various antidepressants.

Weight Gain

Nearly all antidepressants have the potential to cause weight gain with both long-term and short-term use. Unexpected weight gain ranks among the main reasons why people stop taking medications. This side effect can seriously impact self-esteem.

There are several ways how antidepressants can lead to weight gain. These drugs may increase the appetite, causing you to eat more, or slow down the metabolism. Antidepressants can also make you more sedentary through fatigue and tiredness. Some antidepressants (e.g. sertraline and amytripyline) may cause strange food cravings.

SSRIs-induced weight change is related to alteration in serotonin 2C receptor activity, appetite increase, carbohydrate craving, or recovery from depression1,2,3. Weight gain is less likely with SSRIs when they are used for less than 6 months. Paroxetine (Paxil) causes the greatest incidence of weight gain than the other SSRIs.

Tricyclic antidepressants (TCAs) are more likely to cause weight gain than Selective Serotonin Reuptake Inhibitors (SSRIs). Tricyclics appear to slow metabolism and promote carbohydrate cravings4. Because tertiary tricyclic antidepressants (e.g. amitriptyline, imipramine, and doxepin) are stronger histamine blockers than are secondary tricyclics (e.g. desipramine and nortriptyline) the tertiary tricyclic drugs are more likely to cause weight gain.

Mirtazapine (Remeron) has been associated with significant weight gain and may be placed between the SSRIs and the TCAs in terms of relative risk for gaining extra pounds. Mirtazapine contributes to weight gain through blockade of histamine H1 and serotonin 2C receptors. The weight gain may occur even during the first 4 weeks of treatment with mirtazapine5.

Most likely to cause weight gain: tricyclic antidepressants, monoamine oxidase inhibitors and mirtazepine (Remeron). Among the selective serotonin reuptake inhibitors, paroxetine (Paxil) is the worst offender.

Less likely to cause weight gain (weight-neutral antidepressants): Bupropion (Wellbutrin) is one of the most stimulating antidepressants, and is unlikely to cause weight gain. In fact, bupropion may cause weight loss and sometimes is used "off-label" as weight-loss medicine6.

Venlafaxine (Effexor) and trazodone (Desyrel) are not likely to cause weight gain in the short term and have a low tendency to cause this problem over the long term.

Sexual Side Effects

In fact, sexual dysfunction is a common side effect of all classes of antidepressants, but remains highly unrecognized and underreported. Antidepressants produce a variety of sexual side effects, including erectile dysfunction (impotence), delayed orgasm, anorgasmia, delayed ejaculation, and decreased libido.

Although some side effects get milder or disappear after several weeks of antidepressant treatment sexual difficulties rarely go away with time. The incidence of sexual dysfunction in men is higher than in women.

Suggested causes of sexual side effects include increased serotonin, decreased dopamine, blockade of cholinergic and alpha-1 adrenergic receptors, inhibition of nitric oxide synthetase, and elevation of prolactin levels7. Serotonin tends to diminish sexual function, while dopamine tends to enhance sexual function. So drugs that enhance serotonin or block dopamine tend to decrease sexual activity.

In most cases, once the offending medication is stopped, sexual functioning comes back to normal. But some people are faced with the persistent long-lasting symptoms called post-SSRI sexual dysfunction.

Most likely to cause sexual problems: paroxetine (Paxil), and to a lesser degree fluoxetine (Prozac), citalopram (Celexa), sertraline (Zoloft)9.

Least likely to cause sexual problems: The most "sex-friendly" antidepressant is thought to be bupropion (Wellbutrin)8. Bupropion has stimulating properties. Mirtazapine (Remeron) and trazodone (Desyrel) also cause fewer sexual side effects.

Withdrawal Symptoms

Antidepressant discontinuation syndrome (withdrawal symptoms) occurs upon the abrupt discontinuation or a decrease in dosage of the medication. Antidepressant withdrawal symptoms include: irritability, agitation, anxiety, dizziness, flu-like symptoms, headache, nausea, insomnia, tingling sensations.

Antidepressant discontinuation syndrome is more likely with a long-term treatment and a medication with shorter half-life.

Most likely to cause withdrawal symptoms: Venlafaxine (Effexor) and paroxetine (Paxil), both of which have short half-lives and wash out of the body most quickly, are the most likely of the antidepressants to cause withdrawals.

Least likely to cause withdrawal symptoms: Fluoxetine (Prozac) is the least likely to cause any discontinuation symptoms because it has the longest elimination half-life (7–15 days) and remains in the body longer.

List of Antidepressants

Selective serotonin reuptake inhibitors (SSRIs)

Serotonin and norepinephrine reuptake inhibitors (SNRIs)

Norepinephrine and Dopamine Reuptake Inhibitors (NDRIs)

Tricyclic antidepressants

Noradrenergic and specific serotonergic antidepressants (NaSSAs)

Other antidepressants

Azaspirodecanedione anxiolytics

References

  • 1. Sussman N, Ginsberg D. Effects of psychotropic drugs on weight. Psychiatr Ann 1999; 29:580–594.
  • 2. Benazzi F. Weight gain in depression remitted with antidepressants: pharmacological or recovery effect? Psychother Psychosom 1998; 67:271–274.
  • 3. Bouwer CD, Harvey BH. Phasic craving for carbohydrate observed with citalopram. Int Clin Psychopharmacol 1996; 11:273–278.
  • 4. Fava M. Weight gain and antidepressants. J Clin Psychiatry 2001; 61(suppl 11):37–41.
  • 5. Goodnick PJ, Kremer C. Weight gain during mirtazapine therapy. Prim Psychiatry 1998; 3:103–108.
  • 6. Anderson JW, Greenway FL, Fujioka K, Gadde KM, McKenney J, O'Neil PM. Bupropion SR enhances weight loss: a 48-week double-blind, placebo- controlled trial. Obes Res. 2002 Jul;10(7):633-41. PubMed
  • 7. Keltner NL, McAfee KM, Taylor CL. Mechanisms and treatments of SSRI-induced sexual dysfunction. Perspect Psychiatr Care. 2002 Jul-Sep;38(3):111-6.
  • 8. Clayton AH, McGarvey EL, Abouesh AI, Pinkerton RC. Substitution of an SSRI with bupropion sustained release following SSRI-induced sexual dysfunction. J Clin Psychiatry. 2001 Mar;62(3):185-90.
  • 9. Montejo AL, Llorca G, Izquierdo JA, Rico-Villademoros F. Incidence of sexual dysfunction associated with antidepressant agents: a prospective multicenter study of 1022 outpatients. Spanish Working Group for the Study of Psychotropic-Related Sexual Dysfunction. J Clin Psychiatry. 2001;62 Suppl 3:10-21.


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