A:

Both escitalopram and citalopram are types of selective serotonin reuptake inhibitors (SSRIs). Other SSRIs are sertraline (Zoloft), fluoxetine (Prozac), paroxetine (Paxil), and fluvoxamine (Luvox).

Escitalopram is the left-handed half of citalopram. What does that mean?

Some chemicals can have two forms containing the same elements but still be different. Think about your hands. They are identical. But you cannot put your left glove on your right hand.

Chemicals have left-handed and right-handed forms too. Citalopram (Celexa) contains both the right-handed and the left-handed forms of the drug. S-citalopram (escitalopram, Lexapro) contains only the left-handed form.

Compared to the right-handed molecule, left-handed citalopram is more potent. So an escitalopram dose of 10 to 20 mg is like taking 20 to 40 mg of citalopram.

But this turns out to be no real advantage at all. Escitalopram doesn’t treat depression any faster. It doesn’t have fewer side effects. And it does not give relief to more people.

The side effects of both escitalopram and escitalopram are similar to those of other SSRIs.

Those include:

• Nausea
• Diarrhea
• Dry mouth
• Insomnia
• Dizziness
• Increased sweating
• Fatigue
• Sexual problems

Each person reacts to an antidepressant in his or her own way. So, it helps to have many choices for treating depression. Citalopram and escitalopram are simply two of the many good options.