What antidepressants are available?

There are various medications for the treatment of depression. They can be split up into different groups. This article is mainly about the most commonly used antidepressants:

• Tricyclic antidepressants (TCAs)
• Selective serotonin re-uptake inhibitors (SSRIs)
• Selective serotonin noradrenaline re-uptake inhibitors (SNRIs)

Tricyclic antidepressants have been on the market the longest. They are considered to be first-generation antidepressants. SSRIs and SNRIs are second-generation antidepressants.

The following are prescribed less often:

• Adrenergic alpha-2 receptor antagonists
• Monoamine oxidase (MAO) inhibitors
• Selective noradrenaline re-uptake inhibitors
• Selective noradrenaline/dopamine re-uptake inhibitors
• Melatonin receptor agonists and serotonin 5-HT2C receptor antagonists

There are also medications (like trazodone and lithium) that don't belong to any group, as well as herbal products such as St. John's wort.

How do antidepressants work?

The nerve cells in our brain use various chemicals to pass on signals. Even though not all details are known, experts believe that depression is caused by an imbalance of certain chemical messengers (neurotransmitters) like serotonin, which means that signals can't be passed along the nerves properly. Antidepressants aim to increase the availability of these chemicals. The various drugs do that in different ways.

What does the treatment involve?

Antidepressants are usually taken daily. The goal in the first few weeks and months is to relieve the symptoms and, where possible, make the depression go away. Once that has been achieved, the treatment is continued for at least four to nine months. This continuation therapy is necessary to stop the symptoms from coming back. The medication is sometimes taken for longer to prevent relapses. The duration of treatment also depends on how the symptoms continue to develop over time and whether the depression is likely to return. Some people take antidepressants over many years.

It's important to have regular appointments with your doctor when taking antidepressants. There you can talk about whether the symptoms have improved and whether there are any side effects. The dose will be adjusted if necessary. By no means should you reduce the dose or stop taking the medication on your own. That can make the tablets less effective, or they may cause more side effects.

Towards the end of the treatment, the dose is gradually reduced over the course of several weeks. You may experience temporary sleep problems, nausea or restlessness when coming off antidepressants. These symptoms are especially likely if you suddenly stop taking antidepressants. Sometimes people stop taking their medication as soon as they start feeling better, but that increases the risk of the depression coming back. Unlike many sleeping pills and sedatives, antidepressants don't cause physical dependence or addiction.

How effectively do antidepressants relieve the symptoms?

There are a lot of different medications for treating depression. But it's difficult to predict how well a particular medication will help an individual. So doctors often first suggest taking a drug that they consider to be effective and relatively well tolerated. If it doesn't help as much as expected, it's possible to switch to a different medication. Sometimes a number of different drugs have to be tried before you find one that works.

Studies show that the benefit generally depends on the severity of the depression: The more severe the depression, the greater the benefits will be. In other words, antidepressants are effective against chronic, moderate and severe depression. They don't help in mild depression.

The various antidepressants have been compared in many studies. Overall, the commonly used tricyclic antidepressants (SSRIs and SNRIs) were found to be equally effective. Studies involving adults with moderate or severe depression have shown the following:

• Without antidepressants: About 20 to 40 out of 100 people who took a placebo noticed an improvement in their symptoms within six to eight weeks.
• With antidepressants: About 40 to 60 out of 100 people who took an antidepressant noticed an improvement in their symptoms within six to eight weeks.

In other words, antidepressants improved symptoms in about an extra 20 out of 100 people.

Antidepressants can also relieve long-term symptoms of chronic depressive disorder (dysthymia) and chronic depression, and help make them go away completely.

An antidepressant can already have an effect within one or two weeks. But it may take longer for the symptoms to improve.

Depressive symptoms can also be treated with a combination of two medications. This might lead to a noticeable improvement. In some people it can take a long time for a medication to start helping. Other people still have symptoms even after trying several different medications. You can then discuss the other possible treatment options with your doctor.

How well can antidepressants prevent relapses?

Antidepressants are usually taken for one to two years, and sometimes longer, to prevent relapses. Relapse prevention may be a good idea for people who

• have already had several relapses,
• absolutely want to avoid a relapse, or
• have chronic depression.

Studies involving adults have shown that taking commonly used antidepressants such as TCAs, SSRIs or SNRIs can lower the risk of relapses, but can't completely prevent them:

• Without preventive treatment: About 50 out of 100 people who took a placebo had a relapse within one to two years.
• With preventive treatment: About 23 out of 100 people who took an antidepressant had a relapse within one to two years.

In other words, taking an antidepressant over a long period of time successfully prevented a relapse in an average of 27 out of 100 people.

What are the side effects of antidepressants?

Like all medications, antidepressants can have side effects. Over half of all people who take antidepressants have side effects. They usually occur during the first few weeks of treatment and are less common later on.

Some of these side effects are believed to be a direct consequence of the medication's effect on the brain and are relatively similar among various drugs within the same group. Examples include a dry mouth, headaches, dizziness, restlessness and sexual problems. These kinds of problems are often perceived to be side effects of the medications. But some of them may be caused by the depression itself.

Whether or not someone has side effects, which side effects they have, and how frequent they are will depend on the drug, the dose used, and whether they have just started taking it or have been taking it for some time. And everyone reacts slightly differently to drugs too. The risk of side effects increases if you are also taking other medication. One of the drugs may make the side effects of the other worse. These kinds of drug interactions are common in older people and people with chronic illnesses who are taking several different kinds of medication.

For this reason, it's important to thoroughly discuss the pros and cons of the various medications with your doctor.

Some side effects are more common with particular drugs:

• SSRIs are more likely than tricyclic antidepressants to cause diarrhea, headaches, sleep problems and nausea.
• Compared to SSRIs, tricyclic antidepressants are more likely to cause vision problems, constipation, dizziness, a dry mouth, trembling and difficulty urinating (peeing).

The side effects of tricyclic antidepressants are often worse than those of SSRIs and SNRIs. More people tend to stop taking tricyclic antidepressants because of this: Studies found that about 15 out of 100 people who were taking tricyclic antidepressants did so, compared to around 10 out of 100 people who were taking SSRIs. There's also a greater risk of severe side effects if an overdose of tricyclic antidepressants is taken.

What should you consider when deciding whether or not to take antidepressants?

Whether antidepressants are an option will depend on things like the severity of the symptoms. Other aspects can also play a role in the decision:

• Are you going to psychotherapy or are you planning to?
• Have you taken antidepressants before and did they help?
• How bad do you think the potential side effects are compared to the possible benefits?

The question of side effects can also be key when choosing which drug to take: Some people might be more keen to avoid digestion problems. Others might prefer to avoid dizziness, decreased sex drive or erection problems.

It only makes sense to use antidepressants if the diagnosis is correct. Specialists believe that some people are prescribed antidepressants unnecessarily. The fact that a lot more people take antidepressants nowadays suggests that this is true. They are sometimes already prescribed for milder symptoms, even though it's not clear whether they help in mild depression.

But it's still important to make sure that severe depression is diagnosed and treated properly. Antidepressants can be helpful here, and for some people may be the only way that they can get back into a daily routine or start going to psychotherapy.

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• IQWiG health information is written with the aim of helping people understand the advantages and disadvantages of the main treatment options and health care services.

  Because IQWiG is a German institute, some of the information provided here is specific to the German health care system. The suitability of any of the described options in an individual case can be determined by talking to a doctor. We do not offer individual consultations.

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