Types of antidepressants and their side effects

Antidepressant medications prescribed for depression fall into four different classes of drugs:

• serotonin reuptake inhibitors (SSRIs)
• atypical antidepressants
• tricyclic antidepressants
• monoamine oxidase inhibitors (MAOIs)

SSRIs (selective serotonin reuptake inhibitors)

The SSRIs (selective serotonin reuptake inhibitors) are the most commonly prescribed class of antidepressants. They act on a chemical in the brain called serotonin. The SSRIs include drugs such as Prozac, Zoloft, and Paxil.

The SSRIs are preferred over older classes of antidepressants such as tricyclic antidepressants and MAOIs because their adverse effects are less severe.

Like all antidepressants, SSRIs can cause an increase in suicidal thoughts and behaviors. They also carry a risk for increased hostility, agitation, and anxiety. In adults 65 and older, SSRIs increase the risk for falls, fractures, and bone loss.

The SSRIs can also cause serious withdrawal symptoms if you stop taking them abruptly.

Common side effects of SSRIs include:

Nausea Insomnia Dizziness Weight gain or loss Tremors Sweating

Anxiety and restlessness Decreased sex drive Drowsiness or fatigue Dry mouth Diarrhea or constipation Headaches

Atypical antidepressants

There are a variety of newer atypical antidepressants which target other neurotransmitters either alone or in addition to serotonin.

For example, Wellbutrin blocks the reabsorption of the neurotransmitters dopamine and norepinephrine. On the other hand, trazodone, Cymbalta, Effexor, and Remeron affect both norepinephrine and serotonin (which is why they are sometimes called serotonin and norepinephrine reuptake inhibitors, or SNRIs).

The side effects vary according to the specific drug. However, many of the atypical antidepressants can cause nausea, fatigue, weight gain, sleepiness, nervousness, dry mouth, and blurred vision.

Wellbutrin is less likely to cause sexual side effects than other antidepressants

The atypical medication buproprion, also known by the brand name Wellbutrin, is less likely than the SSRIs to cause sexual dysfunction. It is often prescribed either alone or in addition to an SSRI medication when sexual side effects occur.

Wellbutrin may also be a good choice if fatigue or sleepiness is a major concern, as it tends to be more energizing than other types of antidepressants.

Tricyclic antidepressants

Tricyclics are among the oldest antidepressants. They work by inhibiting the brain’s reuptake or serotonin and norepinephrine. They also partially inhibit the reabsorption of dopamine.

Because the tricyclics have such a broad mechanism of action, they tend to cause more side effects than the other classes of antidepressants. For this reason, the SSRIs and the atypical antidepressants are usually prescribed first.

Tricyclic antidepressants typically take around two weeks to provide symptom relief. Drowsiness is a highly common side effect, particularly in the first few weeks after starting the medication.

The tricyclics cause withdrawal symptoms when discontinued abruptly. Tricyclic antidepressants can also cause an abnormal heart rhythm, so they are not recommended if you have heart problems or seizures.

Common side effects of tricyclic antidepressants include:

Weight gain Loss of sex drive Dizziness and nausea Dry mouth Blurred vision

Constipation Difficulty urinating Sun sensitivity Increased heart rate Disorientation or confusion

MAOIs (Monoamine oxidase inhibitors)

MAOIs (monoamine oxidase inhibitors) are the oldest class of antidepressants. MAOIs have severe interactions with certain foods, drinks, and medications. Combining MAO inhibitors with foods or drinks containing tyramine can result in dangerously high blood pressure, which can lead to a stroke or heart attack. Because of this danger, MAOIs are not typically chosen as a first-line depression treatment.

If your doctor prescribes an MAOI, you will have to carefully monitor what you eat and what drugs you take. Items that are restricted include many cheeses, chocolate, wine, and beer.

Common side effects of MAOIs include:

Dizziness Insomnia Weight gain

Headaches Sexual problems Daytime sleepiness

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