Selective serotonin reuptake inhibitors (SSRIs) are the most frequently prescribed antidepressants. SSRIs are called selective because they affect serotonin rather than other chemicals in the brain. These drugs block the reuptake (removal) of serotonin, which kepps the level of serotonin balanced and helps regulate mood.
SSRIs Affect Serotonin Levels in the Brain
There are currently seven SSRIs drugs on the market in the United States (Table 1). These medications are generally safer than older antidepressants, with fewer side effects and drug interactions. In general, SSRIs have received approval from the FDA as safe and effective treatment of major depressive disorder. Many are also approved for anxiety disorders such as panic disorder, generalized anxiety disorder, and social anxiety disorder. Certain drugs in this category are also approved for the use in obsessive-compulsive disorder, posttraumatic stress disorder (PTSD), premenstrual dysphoric disorder (PMDD), and bulimia.
SSRIs are slightly different in how quickly they work and how long they stay in the body. Their side effects also differ somewhat. Common side effects include nervousness, problems sleeping, headache, dry mouth, nausea, changes in sexual desire, and erectile dysfunction. Nausea can be reduced by taking the medicine with food. Nervousness and insomnia can be reduced by taking the drug just before bedtime. Most adverse effects of SSRIs gradually disappear after a few weeks of therapy.
SSRIs show an effect after 4 to 6 weeks of daily use. If one drug in this category does not work in a particular person, another drug may work.
SSRIs can interact with other medications that also cause increased serotonin levels in the brain. These include other antidepressants, prescription opioids, migraine medications, cocaine, and St. John’s wort (a medical herb used to treat depression). If one or more of these drugs are used with an SSRI, a high level of serotonin in the brain can result in serotonin syndrome. Symptoms such as extreme anxiety, tremors, fast heartbeat, sweating, and confusion require emergency care.
Although SSRIs are not addictive, stopping them abruptly can cause symptoms that mimic withdrawal. A doctor should provide guidelines for slowly tapering off SSRI to avoid symptoms of nausea, dizziness, and fatigue.
Warnings and Precautions
Generally, SSRIs are safe and carry few risks. All antidepressants, including SSRIs, can cause an increase in suicidal thoughts or actions, especially in young adults beginning therapy or changing dosages. SSRIs can increase the risk of gastrointestinal bleeding when taken with nonsteroidal anti-inflammatory drugs (NSAIDs), such as aspirin or ibuprofen, or with drugs with a side effect of bleeding, such a warfarin. Taking a drug that lowers stomach acid may be helpful. Women who are considering pregnancy, who are pregnant, or who are breastfeeding should discuss the potential effects of SSRIs on the fetus or infant and consider a break in therapy to avoid exposure.
Several SSRIs are being studied for diseases other than those specified in their FDA labeling. Some of the uses that have shown promise include prevention of migraine, pain of diabetic neuropathy, fibromyalgia, vasovagal syncope (fainting), and premature ejaculation.
Source: US Pharmacist