What are antidepressants?
Antidepressants are medicines used to help people who have depression. Most people with depression get better with treatment that includes these medicines.
How do antidepressants work?
Most antidepressants are believed to work by slowing the removal of certain chemicals from the brain. These chemicals are called neurotransmitters. Neurotransmitters are needed for normal brain function. Antidepressants help people with depression by making these natural chemicals more available to the brain.
How long will I have to take an antidepressant?
Antidepressants are typically taken for at least 4 to 6 months. In some cases, patients and their doctors may decide that antidepressants are needed for a longer time.
Do antidepressants have side effects?
Like most medicines, antidepressant drugs can cause side effects. Not all people get these side effects. Any side effects you have will depend on the medicine your doctor has chosen for you. Your doctor will talk to you about your medicine.
What are the different kinds of antidepressants?
There are many different kinds of antidepressants, including:
- Selective serotonin reuptake inhibitors (SSRIs)
- Tricyclic antidepressants (tricyclics)
SSRIs are a group of antidepressants that includes drugs such as citalopram (brand name: Celexa), Fluoxetine (brand name: Prozac), Paroxetine (brand name: Paxil) and sertraline (brand name: Zoloft). These medicines tend to have fewer side effects than the tricyclics. Some of the side effects that can be caused by SSRIs include dry mouth, nausea, nervousness, insomnia, headache and sexual problems. People taking fluoxetine might also have a feeling of being unable to sit still. People taking paroxetine might feel tired. People taking sertraline might have runny stools and diarrhea.
The tricyclics have been used to treat depression for a long time. They include amitriptyline (brand name: Elavil), desipramine (brand name: Norpramin), imipramine (brand name: Tofranil), nortriptyline (brand names: Aventyl, Pamelor) and trimipramine (brand name: Surmentil). Common side effects caused by these medicines include dry mouth, blurred vision, constipation, difficulty urinating, worsening of glaucoma, impaired thinking and tiredness. These antidepressants can also affect a person’s blood pressure and heart rate.
Other antidepressants exist that have different ways of working than the SSRIs and tricyclics. Commonly used ones are venlafaxine, nefazadone, bupropion, mirtazapine and trazodone. Less commonly used are the monoamine oxidase inhibitors (MAOIs).
Some of the most common side effects in people taking venlafaxine (brand name: Effexor) include nausea and loss of appetite, anxiety and nervousness, headache, insomnia and tiredness. Dry mouth, constipation, weight loss, sexual problems, increased blood pressure, increased heart rate and increased cholesterol levels can also occur.
Nefazodone (brand name: Serzone) can cause headaches, blurred vision, dizziness, nausea, constipation, dry mouth and tiredness. This drug may cause serious liver problems in some patients, although this is not common. bupropion (brand name: Wellbutrin) can cause agitation, insomnia, headache and nausea. Mirtazapine (brand name: Remeron) can cause sedation, increased appetite, weight gain, dizziness, dry mouth and constipation. Some of the most common side effects of trazodone (brand name: Desyrel) are sedation, dry mouth and nausea.
MAOI antidepressants like phenelzine (brand name: Nardil) and tranylcypromine (brand name: Parnate) commonly cause weakness, dizziness, headaches and tremor.
Will antidepressants affect my other medicines?
Antidepressants can have an effect on many other medicines. If you’re going to take an antidepressant, tell your doctor about all the other medicines you take, including over-the-counter medicines and herbal health products (such as St. John’s wort). Ask your doctor and pharmacist if any of your regular medicines can cause problems when combined with an antidepressant.
Taking an MAOI antidepressant at the same time as any other antidepressants or certain over-the-counter medicines for colds and flu can cause a dangerous reaction. Your doctor will also tell you what foods and alcoholic beverages you should avoid while you are taking an MAOI. You should not take an MAOI unless you clearly understand what medications and foods to avoid. If you are taking an MAOI and your doctor wants you to start taking one of the other antidepressants, he or she will have you stop taking the MAOI for a while before you start the new medicine. This gives the MAOI time to clear out of your body.
Revision date: June 22, 2011
Last revised: by Janet A. Staessen, MD, PhD