Types of antidepressants
There are several classes of antidepressants; within each class there are many individual medications. While all antidepressants work well overall, no drug or type of drug works equally well for everyone who takes it. You may be advised to try another type of antidepressant or to use a combination of antidepressants to seek relief from your distress.
The different types of antidepressants are listed below in the order in which they are most commonly prescribed.
SSRIs—selective serotonin reuptake inhibitors
This group of drugs, including fluoxetine (Prozac)*, paroxetine (Paxil), fluvoxamine (Luvox), citalopram (Celexa), escitalopram (Cipralex) and sertraline (Zoloft), is usually the first choice for treatment of depression and anxiety problems. These medications are known to have milder side-effects than some other antidepressants. Buspirone (Buspar) is similar to SSRIs and has been found to help with anxiety but not depression.
Common side-effects include nausea, vomiting, diarrhea, weight gain, dry mouth, headaches, anxiety, sedation and a decrease in sexual desire and response. This group of drugs may also cause a jittery or restless feeling and sleep difficulties, such as problems falling asleep, waking in the night, vivid dreams or nightmares.
SNRIs—serotonin and norepinephrine reuptake inhibitors
This class of medications includes venlafaxine (Effexor), duloxetine (Cymbalta) and desvenlafaxine (Pristiq). These drugs are used to treat depression, anxiety problems and chronic pain.
Common side-effects include nausea, drowsiness, dizziness, nervousness or anxiety, fatigue, loss of appetite and sexual problems. In higher dosage, these medications may increase blood pressure.
NDRIs—norepinephrine and dopamine reuptake inhibitors
The medication available in this class is bupropion (Wellbutrin, Zyban). When used to treat depression, it is often given for its energizing effects, in combination with other antidepressants. It is also used to treat attention-deficit/hyperactivity disorder and as a smoking cessation aid.
Common side-effects are jitteriness and insomnia.
NaSSAs—noradrenergic and specific serotonergic antidepressants
Mirtazapine (Remeron), the medication available in this class, is the most sedating antidepressant, making it a good choice for people who have insomnia or who are very anxious. This medication also helps to stimulate appetite.
Common side-effects are drowsiness and weight gain.
This older group includes amitriptyline (Elavil), maprotiline (Ludiomil), imipramine (Tofranil), desipramine (Norpramin), nortriptyline (Novo-Nortriptyline) and clomipramine (Anafranil).
Because these drugs tend to have more side-effects than the newer drugs, they are not often a first choice for treatment. However, when other drugs do not provide relief from severe depression, these drugs may help.
Common side-effects include dry mouth, tremors, constipation, sedation, blurred vision, difficulty urinating, weight gain and dizziness. Because cyclics may cause heart rhythm abnormalities, your doctor should give you an electrocardiogram (ECG) before you take this medication.
MAOIs—monoamine oxidase inhibitors
Monoamine oxidase inhibitors, or MAOIs, such as phenelzine (Nardil) and tranylcypromine (Parnate) were the first class of antidepressants. MAOIs are effective, but they are not often used because people who take them must follow a special diet.
A newer MAOI, moclobemide (Manerix), can be used without dietary restrictions; however, it may not be as effective as other MAOIs.
Common side-effects include a change of blood pressure when moving from a sitting to a standing position (orthostatic hypotension), insomnia, swelling and weight gain.
Do antidepressants increase the risk of suicide?
One of the symptoms of depression is suicidal thought and behaviour. When starting medication treatment for depression, people may be at an increased risk of suicide. One possible explanation is that it may be related to the increase in energy that comes early in treatment, before improvement in mood. In other words, antidepressants may give some people the energy to act on their suicidal thoughts.
Antidepressants can also cause feelings of agitation, restlessness and detachment. These feelings may resemble symptoms of anxiety and may add to, rather than relieve, feelings of hopelessness and despair. Some people may become suicidal or violent. This reaction to antidepressants is thought to occur in about four per cent of people who take them, with the risk being highest in the first few weeks of treatment.
Before starting treatment, it is important to prepare for the possibility of feeling worse before you feel better. Know what supports are available to you and who you can call. When you begin treatment, monitor your thoughts and moods, and communicate any thoughts of hurting yourself or others with your doctor, a crisis line or the emergency department.
If you experience an increase in suicidal thinking or anxiety, your doctor can help you decide if you should stop taking the medication or if you should try to be patient and give the medication a chance to work.
*Medications are referred to in two ways: by their generic name and by their brand or trade names. Brand names available in Canada appear here in brackets.