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.

What are the different kinds of antidepressants?

Antidepressants are put into groups based on which chemicals in the brain they affect. There are many different kinds of antidepressants, including:

• Selective serotonin reuptake inhibitors (SSRIs)
• citalopram (brand name: Celexa)
• escitalopram (brand name: Lexapro)
• fluoxetine (brand name: Prozac)
• paroxetine (brand names: Paxil, Pexeva)
• sertraline (brand name: Zoloft)

These medicines tend to have fewer side effects than other antidepressants. Some of the side effects that can be caused by SSRIs include dry mouth, nausea, nervousness, insomnia, sexual problems and headache.

• Tricyclics
• amitriptyline (brand name: Elavil)
• desipramine (brand name: Norpramin)
• imipramine (brand name: Tofranil)
• nortriptyline (brand name: Aventyl, Pamelor)

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.

• Serotonin and norepinephrine reuptake inhibitors (SNRIs)
• venlafaxine (brand name: Effexor)
• duloxetine (brand name: Cymbalta)

Some common side effects caused by these medicines include nausea and loss of appetite, anxiety and nervousness, headache, insomnia and tiredness. Dry mouth, constipation, weight loss, sexual problems, increased heart rate and increased cholesterol levels can also occur.

• Norepinephrine and dopamine reuptake inhibitors (NDRIs)
• bupropion (brand name: Wellbutrin)

Some of the common side effects in people taking NDRIs include agitation, nausea, headache, loss of appetite and insomnia. It can also cause increase blood pressure in some people.

• Combined reuptake inhibitors and receptor blockers
• trazodone (brand name: Desyrel)
• nefazodone (brand name: Serzone)
• maprotiline
• mirtazpine (brand name: Remeron)

Common side effects of these medicines are drowsiness, dry mouth, nausea and dizziness. If you have liver problems, you should not take nefazodone. If you have seizures, you should not take maprotiline.

• Monamine oxidase inhibitors (MAOIs)
• isocarboxazid (brand name: Marplan)
• phenelzine (brand name: Nardil)
• tranlcypromine (brand name: Parnate)

MAOIs are used less commonly than the other antidepressants. They can have serious side effects, including weakness, dizziness, headaches and trembling. Taking an MAOI antidepressant while you're taking another antidepressant 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.

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.