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Antidepressants are used most often for serious depressions, but they can also be helpful for some milder depressions. Antidepressants are not "uppers" or stimulants, but rather take away or reduce the symptoms of depression and help depressed people feel the way they did before they became depressed.
The doctor chooses an antidepressant based on the individual's symptoms. Some people notice improvement in the first couple of weeks; but usually the medication must be taken regularly for at least six weeks and, in some cases, as many as eight weeks before the full therapeutic effect occurs. If there is little or no change in symptoms after six or eight weeks, the doctor may prescribe a different medication or add a second medication such as lithium, to augment the action of the original antidepressant. Because there is no way of knowing beforehand which medication will be effective, the doctor may have to prescribe first one and then another. To give a medication time to be effective and to prevent a relapse of the depression once the patient is responding to an antidepressant, the medication should be continued for six to 12 months, or in some cases longer, carefully following the doctor's instructions.
When a patient and the doctor feel that medication can be discontinued, withdrawal should be discussed as to how best to taper off the medication gradually. Never discontinue medication without talking to the doctor about it. For those who have had several bouts of depression, long-term treatment with medication is the most effective means of preventing more episodes.
Dosage of antidepressants varies, depending on the type of drug and the person's body chemistry, age and, sometimes, body weight. Traditionally, antidepressant dosages are started low and raised gradually over time until the desired effect is reached without the appearance of troublesome side effects. Newer antidepressants may be started at or near therapeutic doses.
Early antidepressants. From the 1960s through the 1980s, tricyclic antidepressants (named for their chemical structure) were the first line of treatment for major depression. Most of these medications affected two chemical neurotransmitters, norepinephrine and serotonin. Though the tricyclics are as effective in treating depression as the newer antidepressants, their side effects are usually more unpleasant; thus, today tricyclics such as imipramine, amitriptyline, nortriptyline and desipramine are used as a second- or third-line treatment. Other antidepressants introduced during this period were monoamine oxidase inhibitors (MAOIs). MAOIs are effective for some people with major depression who do not respond to other antidepressants. They are also effective for the treatment of panic disorder and bipolar depression. MAOIs approved for the treatment of depression are phenelzine (Nardil), tranylcypromine (Parnate), and isocarboxazid (Marplan). Because substances in certain foods, beverages, and medications can cause dangerous interactions when combined with MAOIs, people on these agents must adhere to dietary restrictions. This has deterred many clinicians and patients from using these effective medications, which are in fact quite safe when used as directed.
The past decade has seen the introduction of many new antidepressants that work as well as the older ones but have fewer side effects. Some of these medications primarily affect one neurotransmitter, serotonin, and are called selective serotonin reuptake inhibitors (SSRIs). These include fluoxetine (Prozac), sertraline (Zoloft), fluvoxamine (Luvox), paroxetine (Paxil), and citalopram (Celexa).
The late 1990s ushered in new medications that, like the tricyclics, affect both norepinephrine and serotonin but have fewer side effects. These new medications include venlafaxine (Effexor) and nefazadone (Serzone). Cases of life-threatening hepatic failure have been reported in patients treated with nefazodone (Serzone). Patients should call the doctor if the following symptoms of liver dysfunction occur — yellowing of the skin or white of eyes, unusually dark urine, loss of appetite that lasts for several days, nausea or abdominal pain.
Other newer medications chemically unrelated to the other antidepressants are the sedating mirtazepine (Remeron) and the more activating bupropion (Wellbutrin). Wellbutrin has not been associated with weight gain or sexual dysfunction but is not used for people with, or at risk for, a seizure disorder.
Each antidepressant differs in its side effects and in its effectiveness in treating an individual person, but the majority of people with depression can be treated effectively by one of these antidepressants.
Side Effects of Antidepressant Medications
Antidepressants may cause mild, and often temporary, side effects (sometimes referred to as adverse effects) in some people. Typically, these are not serious. However, any reactions or side effects that are unusual, annoying or that interfere with functioning should be reported to the doctor immediately.
Most Common Side Effects of Tricyclic Antidepressants
- Dry mouth — it is helpful to drink sips of water; chew sugarless gum; brush teeth daily.
- Constipation — bran cereals, prunes, fruit and vegetables should be in the diet.
- Bladder problems — emptying the bladder completely may be difficult, and the urine stream may not be as strong as usual. Older men with enlarged prostate conditions may be at particular risk for this problem. The doctor should be notified if there is any pain.
- Sexual problems — sexual functioning may be impaired; if this is worrisome, it should be discussed with the doctor.
- Blurred vision — this is usually temporary and will not necessitate new glasses. Glaucoma patients should report any change in vision to the doctor.
- Dizziness — rising from the bed or chair slowly is helpful.
- Drowsiness as a daytime problem — this usually passes soon. A person who feels drowsy or sedated should not drive or operate heavy equipment. The more sedating antidepressants are generally taken at bedtime to help sleep and to minimize daytime drowsiness.
- Increased heart rate — pulse rate is often elevated. Older patients should have an electrocardiogram (EKG) before beginning tricyclic treatment.
Side Effects of Newer Antidepressants, Including SSRIs
- Sexual problems — fairly common, but reversible, in both men and women. The doctor should be consulted if the problem is persistent or worrisome.
- Headache — this will usually go away after a short time.
- Nausea — may occur after a dose, but it will disappear quickly.
- Nervousness and insomnia (trouble falling asleep or waking often during the night) — these may occur during the first few weeks; dosage reductions or time will usually resolve them.
- Agitation (feeling jittery) — if this happens for the first time after the drug is taken and is more than temporary, the doctor should be notified.
Any of these side effects may be amplified when an SSRI is combined with other medications that affect serotonin. In the most extreme cases, such a combination of medications (e.g., an SSRI and an MAOI) may result in a potentially serious or even fatal "serotonin syndrome," characterized by fever, confusion, muscle rigidity, and cardiac, liver or kidney problems.
The small number of people for whom MAOIs are the best treatment need to avoid taking decongestants and consuming certain foods that contain high levels of tyramine, such as many cheeses, wines and pickles. The interaction of tyramine with MAOIs can bring on a sharp increase in blood pressure that can lead to a stroke. The doctor should furnish a complete list of prohibited foods that the individual should carry at all times. Other forms of antidepressants require no food restrictions. MAOIs also should not be combined with other antidepressants, especially SSRIs, due to the risk of serotonin syndrome.
Safety Reminder for All Medications
Medications of any kind — prescribed, over-the-counter, or herbal supplements — should never be mixed without consulting the doctor; nor should medications ever be borrowed from another person. Other health professionals who may prescribe a drug — such as a dentist or other medical specialist — should be told that the person is taking a specific antidepressant and the dosage. Some drugs, although safe when taken alone, can cause severe and dangerous side effects if taken with other drugs.
Alcohol (wine, beer and hard liquor) or street drugs, may reduce the effectiveness of antidepressants and their use should be minimized or, preferably, avoided by anyone taking antidepressants. Some people who have not had a problem with alcohol use may be permitted by their doctor to use a modest amount of alcohol while taking one of the newer antidepressants. The potency of alcohol may be increased by medications since both are metabolized by the liver; one drink may feel like two.
Although not common, some people have experienced withdrawal symptoms when stopping an antidepressant too abruptly. Therefore, when discontinuing an antidepressant, gradual withdrawal is generally advisable.
Questions about any antidepressant prescribed, or problems that may be related to the medication, should be discussed with the doctor and/or the pharmacist.
Source: National Institutes of Health