Prozac causes insomnia


Antidepressants have a mood-enhancing and anxiety-relieving effect. Some antidepressants are more likely to calm you down, while others are more likely to increase your drive. Antidepressants are used in the treatment of depression, anxiety disorders, and obsessive-compulsive disorder.

Patients taking antidepressants are often affected by side effects, which is why they are only prescribed for more severe depressive illnesses if possible. Side effects occur at the beginning of treatment and upon discontinuation, the latter often in the form of restlessness and mood swings, dizziness, tingling in the limbs and sleep disorders, which is why the intake is reduced ("tapered") over a period of several weeks to months. The side effects of discontinuation are experienced by some patients as so uncomfortable that they resume taking it again.

To the v. a. Side effects observed at the beginning of treatment, but which usually subside as the treatment progresses, include:

  • Dry mouth, sweating
  • Visual disturbances and dizziness
  • Trembling hands, tiredness
  • Fluctuations in blood pressure, rarely cardiac arrhythmias (when using tri- and tetracyclics).
  • Changes in the blood count caused by tri- and tetracyclics with weak immune systems and severe infections. Continuous monitoring of the blood count is therefore necessary.
  • Weight change: some antidepressants stimulate the appetite, which is initially quite desirable with the often existing loss of appetite, but often goes beyond that. Other antidepressants (especially when you start taking them) suppress your appetite.
  • The weight gain can lead to a worsening of the blood sugar control in diabetics.
  • Increased aggressive behavior when taking SSRIs
  • Decreasing sexual desire, especially in women, rarely the opposite. Impotence, or at least delayed ejaculation, is very common in men.
  • Suicide risk: All antidepressants can increase suicidal tendencies. This has been particularly well documented for the SSRIs paroxetine and venlafaxine, but according to the current state of knowledge it also applies to other, modern as well as older, antidepressants.

Ineffectiveness. In some patients, the prescription of an antidepressant does not seem to have any effect at all - apart from the case of underdosing, why and which patients this affects is unknown. The best thing to do is to switch to another antidepressant, which is often effective.

Since the spectrum of side effects differs between the individual antidepressants, the experienced doctor can individually select the substance that is likely to have the best and least side effects by carefully weighing the symptoms, accompanying illnesses and interests of the patient. Unfortunately, quite a few doctors prescribe antidepressants without the appropriate specialist knowledge. In case of doubt, you should therefore urge a referral to a suitable specialist (psychiatrist).

Pregnant women, children and adolescents are only prescribed antidepressants if there is an urgent need, because the risk of side effects is high: Children and adolescents are more likely to behave aggressively but also to have suicidal thoughts.

Antidepressants are divided into three groups according to their chemical structure: tricyclic antidepressants, MAOIs and the newer SSRIs (selective serotonin reuptake inhibitors). The correct use of antidepressant substances requires an exact diagnosis and precise knowledge of the range of effects and side effects of the drugs. For example, in the case of arousal and anxiety in the context of depression, the doctor will choose a calming antidepressant, whereas in the case of uninspired depressives, a substance that increases the drive will be more likely. In doing so, he must keep in mind that the drive-enhancing effect occurs more quickly than the mood improvement, which increases the risk of suicide at the start of therapy in particularly vulnerable patients. Combinations of antidepressants and transquilizers (sedatives) are therefore particularly useful in the first few weeks of treatment. In terms of effectiveness, the classic tricyclic and tetracyclic antidepressants are still unsurpassed, while the newer antidepressants (SSRIs) are often better tolerated.

Tri- and tetracyclic antidepressants (Tricyclics, Tetracyclics), whose name comes from their chemical structure of three (tri) or four (tetra) rings, improve the balance between the messenger substances serotonin and norepinephrine in the brain, which is disturbed in depression. However, they only take effect after 3-6 weeks. And only then can the doctor and patient determine whether the drug and dosage help or whether it is necessary to switch to another drug. At the start of therapy, the dose is increased ("crept in") in small steps in order to minimize side effects and, if necessary, to be able to stop the treatment even if the dosage is still moderate. Tricyclics are the drug of choice during pregnancy.

SSRIs (Selective serotonin reuptake inhibitors) cause a neurotransmitter in the brain, serotonin, which is important for the basic mood, to be broken down more slowly. This is intended to have a mood-enhancing, activating and anxiety-relieving effect. Since the SSRIs are often better tolerated than z. B. tricyclic antidepressants, they were previously prescribed as the drug of first choice for depression and anxiety disorders. However, due to the weaker antidepressant effect, the risk-benefit analysis of SSRIs is viewed more critically in more recent studies than in the past, so that the extent to which the generous prescription of SSRIs is medically justified is sometimes controversial. The effectiveness of the two SNRIs (Serotonin and norepinephrine reuptake inhibitors) Venlafaxine and duboxetine (see table) has now been confirmed. The Institute for Quality and Efficiency in Health Care (IQWIG) has tested both substances and proven their effectiveness. However, according to IQWIG, they have slightly more side effects than antidepressants that only act on serotonin.

SSRIs are better tolerated, but by no means free of side effects. The following side effects often occur primarily at the beginning of therapy, but improve as treatment progresses:

  • Dry mouth, sweating, dizziness
  • Loss of appetite, nausea
  • Agitation, anxiety, sleep disorders
  • Aggressive behavior (rare)
  • fatigue
  • Changes in sexuality: The sexual desire can be increased or decreased, in men there can be delays in ejaculation.

MAOIs. The Monoamine oxidase is an enzyme that breaks down certain messenger substances in the brain (noradrenaline, serotonin). If this degradation is caused by drugs (MAOIs, Monoamine oxidase inhibitors), the concentration of messenger substances in the brain increases. The result: the mood brightens, the drive is increased.

MAO inhibitors are only used as reserve medication when other antidepressants do not work, whereby in Germany only moclobemide (Aurorix®) is used. Side effects are unfortunately very common and include: agitation, anxiety and sleep disorders, cardiac arrhythmias, nausea and diarrhea.


Dr. med. Arne Schäffler, Gisela Finke in: Gesundheit heute, edited by Dr. med. Arne Schäffler. Trias, Stuttgart, 3rd edition (2014). Revision and update: Dr. med. Sonja Kempinski | last changed on at 14:31