Antidepressants

What are antidepressants?

Antidepressants are prescription medications that can help relieve symptoms of depression and several other conditions. There are several classes, which work in different ways and have different side-effect profiles.

What they’re used for

Depending on the medication, antidepressants may be prescribed for:

• Depression
• Anxiety disorders, including generalized anxiety, panic and social anxiety
• Obsessive-compulsive disorder
• PTSD
• Some chronic pain conditions and other uses a clinician may consider

How they work

Most antidepressants affect brain chemical messengers (neurotransmitters) such as serotonin and norepinephrine. Scientists believe the benefits also involve longer-term changes in how brain circuits adapt, which may help explain why they take weeks to work.

Main types

• SSRIs (selective serotonin reuptake inhibitors): often a first choice because they are generally well tolerated.
• SNRIs (serotonin-norepinephrine reuptake inhibitors): affect both serotonin and norepinephrine.
• Atypical antidepressants: such as bupropion and mirtazapine, which work in different ways.
• Tricyclic antidepressants (TCAs): an older class, used less often because of side effects.
• MAOIs (monoamine oxidase inhibitors): an older class with important food and drug interactions.

How they’re taken

Antidepressants are usually taken by mouth once or more daily. Prescribers typically start at a lower dose and adjust gradually, based on response and side effects. Your prescriber and pharmacist will give instructions specific to your medication — this page does not provide dosing guidance.

Common side effects

Side effects vary by medication and person. Common ones include:

• Nausea or upset stomach
• Headache
• Sleep changes (drowsiness or insomnia)
• Sexual side effects, such as reduced desire or difficulty with orgasm
• Dry mouth, sweating
• Weight changes (with some medications)

Many early side effects improve within the first weeks.

Serious side effects

Seek medical advice promptly if you notice:

• Worsening depression, new or increased thoughts of suicide, or unusual changes in behavior
• Signs of serotonin syndrome — agitation, confusion, fast heart rate, high temperature, muscle stiffness or twitching — which is a medical emergency
• Signs of mania, such as unusually elevated mood, racing thoughts or reduced need for sleep
• Unusual bleeding or bruising
• Severe allergic reactions

Warnings

• Boxed warning: increased risk of suicidal thoughts and behaviors in people under 25, especially early in treatment.
• Bipolar disorder: antidepressants used alone can trigger mania in some people with bipolar disorder. Tell your prescriber about any history of elevated mood.
• Stopping treatment: stopping suddenly can cause discontinuation symptoms, such as dizziness, irritability, flu-like feelings and “brain zaps.” Changes should be planned with your prescriber.
• Pregnancy and breastfeeding: discuss risks and benefits with your healthcare team.

Interactions

Antidepressants can interact with other medications and supplements, including other antidepressants, some migraine medications (triptans), certain pain medications, blood thinners, St. John’s wort and alcohol. MAOIs have particularly important interactions. Always tell your prescriber and pharmacist about everything you take.

Questions to ask your healthcare professional

• Why are you recommending this medication for me, and what are the alternatives?
• How long before I might notice a difference?
• What side effects should I watch for, and which ones mean I should call you?
• Does this interact with anything else I take?
• How will we know if it is working, and when will we review it?
• How long might I take it, and how would I stop safely?