A newer type of antidepressant medication was introduced into the U.S. in the 1980s, beginning with Prozac (fluoxetine). These drugs offer a different chemical structure than the cyclic antidepressants and therefore produce different effects on the brain. Primarily they assist the brain in maintaining enough supply of the neurotransmitter serotonin. For instance, researchers associate a deficiency of serotonin with depression and obsessive-compulsive disorder and implicate it in panic disorder and other psychological problems. These medications are called selective serotonin reuptake inhibitors, abbreviated SSRIs.

Possible Benefits. SSRIs can be helpful for depression, panic disorder, social anxiety, obsessive compulsive disorder, generalized anxiety and PTSD. They are well tolerated medications that are safe for medically ill or frail patients and safe in overdose. There are no withdrawal effects unless the patient stops them abruptly, and no dependency develops. They generally do not promote weight gain.

Possible Disadvantages. It takes four to six weeks to notice significant therapeutic benefits from the SSRIs. The full range of benefits can take twelve weeks. Patients often experience a temporary worsening of anxiety symptoms during the first two weeks of treatment. Abrupt discontinuation of the SSRIs could cause flu-like symptoms. All the SSRIs can be expensive.

SSRIs cause sexual problems more than other antidepressants or benzodiazopines. In fact, this may be their principle limitation, occurring in as many as 35 to 40% of patients. It is unclear whether these problems are evident in one SSRI more than others. Consult your physician regarding use during pregnancy or breast-feeding.

Possible Side Effects. Nausea, insomnia, headaches, sexual difficulties, initial agitation.

Fluoxetine (Prozac)

Possible Benefits. Helpful for depression, panic disorder, social anxiety, obsessive compulsive disorder, generalized anxiety and PTSD. Current research suggests some benefits for social anxiety. Few side effects. No dependency. A well tolerated and safe medication.

Possible Disadvantages. May cause anxiety or insomnia. Therapeutic response can take four to six weeks. It is best to be off of Prozac for two menstrual cycles prior to attempting pregnancy. Do not use when breast-feeding.

Possible Side Effects. Nervousness and tremors, sweating, nausea, anxiety, diarrhea, difficulty falling asleep or frequent awakenings, difficulty achieving orgasm, decreased libido, headache, loss of appetite, postural hypotension, drowsiness or fatigue, upset stomach.

Dosages Recommended by Investigators. Prozac comes in 10 and 20 mg capsules and liquid oral solution that the patient usually takes in the morning. If you have a side effect of upset stomach, take it with food. Typically the initial dose is low, at 2.5 to 5 mg per day and gradually raised to 20 mg per day. If there is no response to this dose after four to eight weeks, raise the dose by 20 mg a week until there is a response, to a maximum dose of 80 mg.

Sertraline (Zoloft)

Possible Benefits. Helpful for depression, panic disorder, social anxiety, obsessive compulsive disorder, generalized anxiety and PTSD. Low level of nervousness or agitation as side effect.

Possible Disadvantages. May cause anxiety or insomnia. Therapeutic response can take four to six weeks. Get your physician's approval before use during pregnancy or breast-feeding.

Possible Side Effects. Headache, dry mouth, sleepiness, dizziness, tremors, diarrhea, agitation, confusion, nausea, delayed ejaculation in men.

Dosages Recommended by Investigators. Start with 50 mg in morning or evening. Maximum dose is 200 mg. Taper slowly.

Paroxetine (Paxil)

Possible Benefits. Helpful for depression, panic disorder, social anxiety, obsessive compulsive disorder, generalized anxiety and PTSD.

Possible Disadvantages. Therapeutic response can take four to six weeks. Discuss possible pregnancy or breast-feeding with your physician.

Possible Side Effects. Nausea, sleepiness, constipation, dry mouth, dizziness, insomnia, delayed orgasm, weight gain.

Dosages Recommended by Investigators. Start with 10 mg once a day. If no response after several weeks, can increase 10 mg per week up to 60 mg. For OCD the minimum therapeutic dose is often 40 mg.

Fluvoxamine (Luvox)

Possible Benefits. Helpful for depression, panic disorder, social anxiety, obsessive compulsive disorder, generalized anxiety and PTSD.

Possible Disadvantages. Therapeutic response can take four to six weeks. Avoid alcohol. Do not take during pregnancy or breast-feeding.

Possible Side Effects. Nausea, sleepiness, insomnia, dry mouth, headache, dizziness, delayed ejaculation.

Dosages Recommended by Investigators. Start at 50 mg at night. Increase to between 100 and 300 mg per day. Doses over 100 mg should be divided into morning and night, with larger dose at night. To reduce nausea, take with food.

(Escitalopram oxalate) Lexapro

Possible Benefits. Helpful for generalized anxiety disorder, social anxiety disorder, PTSD and depression.

Possible Disadvantages. Therapeutic response can take four to six weeks. Avoid alcohol. Do not take during pregnancy or breast-feeding.

Possible Side Effects. Nausea, diarrhea, constipation, loss of appetite, stomach pain, dizziness, drowsiness, trouble sleeping, fatigue, increased sweating, or dry mouth may occur.

Dosages Recommended by Investigators. 10 mg per day, may be increased to 20 mg.

Citalopram (Celexa)

Possible Benefits. Helpful for depression, panic disorder, social anxiety, obsessive compulsive disorder, generalized anxiety and PTSD.

Possible Disadvantages. Therapeutic response can take four to six weeks. Avoid alcohol. Do not take during pregnancy or breast-feeding.

Possible Side Effects. Nausea, vomiting, lack of appetite, diarrhea, drowsiness, dizziness, trouble sleeping, dry mouth, muscle/joint pain, fatigue, or yawning may occur.

Dosages Recommended by Investigators. start with 10 mg per day, may be increased to 20-60 mg.