SSRI antidepressants are probably the best known to generalist physicians, and often the first medications tried. These all work very similarly, but individuals may still have different reactions to different medications. The side effect profile is generally mild, but about half of people will have some side effects early in treatment. SSRIs can cause headache, nausea, diarrhea, decreased sexual functioning, dizziness, sweating, and anxiety or restlessness, and bruising or changes in menstrual cycles. These medications may also cause activation or sedation.
Activation is an effect similar to drinking several cups of coffee.
Someone might experience this pleasantly as improved energy or concentration, or negatively as insomnia or jitteriness, or worsened anxiety in the short run. Sedation might be experienced positively as calmness or good sleep or lessened anxiety, or negatively as drowsiness or fatigue. Very long half-life, meaning it takes a long time to eliminate from the body. This can minimize or eliminate side effects from withdrawal, even if stopped suddenly. Very low incidence of causing weight gain.