Choosing a medication
One day, a detailed knowledge of the biology of depression may help us to predict which antidepressant will work best for each person. Right now, though, psychiatrists and doctors who prescribe antidepressants choose a particular drug and dosage based on many factors, including the following:
1. Diagnosis. Certain drugs work better for specific symptoms and types of depression. For example, some antidepressants may be better when insomnia is an issue. The severity of your illness or the presence of anxiety, obsessions, or compulsions may also dictate the choice of one drug over another.
2. Side effects. You may first want to choose a drug based on which side effect you most want to avoid. Medications vary in the chances they will cause such problems as sexual effects, weight gain, or sedation. You can find information on medication side effects in the following sections and in Table 3.
3. Age. As you age, your body tends to break down drugs more slowly. Thus, older patients may need a lower dosage. For children, only a few medications have been studied carefully.
4. Health. If you have certain health problems, it's best to avoid certain drugs. For example, your doctor will want to consider factors such as heart disease or neurological illnesses when recommending a drug. For this reason, it's important to discuss medical problems with a primary care doctor or psychiatrist before starting an antidepressant.
5. Medications, supplements, and diet. When combined with certain drugs or substances, antidepressants may not work as well, or they may have worrisome or dangerous side effects. For example, combining an SSRI or the herbal remedy St. John's wort with another type of antidepressant known as a monoamine oxidase inhibitor (MAOI) can boost serotonin to dangerous and sometimes fatal levels. Likewise, mixing St. John's wort with other drugs — including certain drugs to control HIV infection, cancer medications, and birth control pills — might lower their effectiveness. Women receiving tamoxifen for breast cancer should take an antidepressant that does not interfere with tamoxifen's effectiveness. Eating certain foods, such as cheeses and pickles, while taking an MAOI can cause a dangerous rise in blood pressure.
6. Alcohol or drugs. Alcohol and other substances can cause depression and make antidepressants less effective. Doctors often treat alcohol or drug addiction first if they believe either is causing the depression. In many instances, simultaneous treatment for addiction and depression is warranted.
7. Personal and family mental health and medication history. If you or a member of your family has had a good response to a medication in the past, that information may guide your choice. Depending on the nature and course of your depression (for example, if your depression is long-lasting or difficult to treat), you may need a higher dosage or a combination of drugs. This may also be true if an antidepressant has stopped working for you, which may occur after you've used it for some time or after you've stopped and restarted treatment with it.
8. Cost. Since all antidepressants are roughly equivalent in their effectiveness, you won't lose anything by trying a generic form first.
9. Your preference. Once you have learned as much as you can about the treatment options, your doctor will want to know what approach makes most sense given your lifestyle, your interests, and your judgment.