There are many prescription medications for anxiety which are effective, and for the most part, safe. Prescription anxiety medications include the following classes of drugs: selective serotonin reuptake inhibitors (SSRI), serotonin norepinephrine reuptake inhibitors (SNRI), benzodiazepines, buspirone, tricyclic antidepressants (TCA), monoamine oxidase inhibitors (MAOI) and antihypertensive medications (beta blockers). However, prescription medications for anxiety may produce side effects: some mild and a nuisance, while others serious and life-threatening. The following are the 16 biggest side effects of prescription anxiety medications (Stahl, 2008):
- Drowsiness (TCA, benzodiazepine):
- Insomnia (SSRI, SNRI):
- Dry mouth, blurred vision, constipation, urinary retention (TCA, SNRI):
- Loss of libido, anorgasmia (SSRI, SNRI):
- Addictive potential (benzodiazepine):
- Feeling agitated, anxious (SSRI, SNRI):
- Dizziness (TCA, benzodiazepine, buspirone):
- Tremor (SNRI, benzodiazepine):
- Myoclonus (SSRI, SNRI):
- Changes blood pressure and heart rate (SNRI, beta blocker):
- Apathy (SSRI, SNRI):
- Difficulty concentrating (benzodiazepine):
- Diarrhea, gastrointestinal upset (SSRIs, SNRIs):
- Nausea, vomiting (SSRI, SNRI, buspirone):
- Weight gain (TCA):
- Hypertension from drug-drug interactions (MAOI):
Sedation (drowsiness) can be induced by TCAs and benzodiazepines. This side effect is also utilized clinically to help with insomnia. Indeed, TCAs and benzodiazepines are prescribed as hypnotic medications to help with going to sleep and staying asleep. With this side effect, one must be careful when driving.
SSRIs and SNRIs may induce nocturnal awakenings and disrupt slow-wave sleep. If the insomnia continues, then either the clinician switches to another anxiolytic or adds a second drug (ie hypnotic medication) to deal with this side effect.
TCAs and SNRIs may cause side effects of dry mouth, blurred vision, constipation and urinary retention. This constellation of side effects is also known as an anticholinergic effect. As you can imagine, anticholinergic effects can be a significant nuisance and can affect compliance.
Sexual dysfunction can be a side effect with SSRIs and SNRIs. Delayed ejaculation or even inhibited ejaculation may occur. Indeed, SSRIs are effective for those with premature ejaculation (Mohamed and Rany, 2007). Decreased libido may also occur with SSRI and SNRIs. Sexual dysfunction as a side effect is one of the main reasons males discontinue taking the medication.
Benzodiazepines can be addictive, and tolerance may develop with chronic use, requiring more of the drug for similar effect when first starting the drug. So if one starts a benzodiazepine for anxiety then becomes addicted to it, then that person trades one problem for another one. As a psychiatrist, I only prescribe benzodiazepines on a temporary, short-term basis, until the anxiety subsides and other treatments with no addictive potential can be instituted.
When first starting an SSRI or SNRI, one may experience agitation or anxiety, which tends to go away with time. However, the agitation or anxiety may be severe enough to force one to stop taking the medication altogether. Indeed, anxiety and panic attacks may be induced when first starting an SSRI or SNRI, which defeats the purpose of taking the medication in the first place! Fluoxetine and venlafaxine are notorious for this.
TCAs, benzodiazepines and buspirone may cause dizziness. In addition, TCAs can cause dizziness when one stands up too quickly, also known as orthostatic hypotension. This side effect can lead to falls and injuries, so this can be a serious side effect, especially in the elderly.
Tremor can be induced by SNRIs and benzodiazepines. This side effect can make writing and other fine-motor movements difficult.
SSRIs and SNRIs may induce rapid muscle movements during the night, known as myoclonus. These nocturnal jerkings of the limbs can be quite disturbing, as it can affect sleep and make the anxiety worse.
Changes in blood pressure and heart rate may be induced by SNRIs and beta blockers. SNRIs can increase the blood pressure, while beta blockers decrease blood pressure.
Apathy, or loss of the ability to feel pleasure, may be induced by SSRIs and SNRIs. My patients tell me that these medications help their anxiety by helping them not care as much about their worrisome thoughts. But it may go too far to the point of feeling apathetic, which again, trades one problem for another one.
Benzodiazepines can make concentrating difficult. Benzodiazepines act similar to alcohol, so concentrating can be difficult when drinking alcohol, as when one takes benzodiazepines. Being anxious makes it difficult to concentrate already, so this side effect only exacerbates this problem.
Diarrhea and gastrointestinal upset may occur with SSRIs and SNRIs. This can be a major nuisance and may lead to non-compliance.
Nausea and vomiting may be induced by SSRIs, SNRIs and buspirone. One may already be nauseous when anxious, so this only compounds the problem.
TCAs can induce weight gain. This can be a major barrier to continuing treatment, as changes in weight may induce even more anxiety, not to mention the negative health effects of weight gain.
Increases in blood pressure (hypertension) can result from combining MAOIs with decongestants, stimulants, TCAs, SNRIs, norepinephrine reuptake inhibitors, norepinephrine dopamine reuptake inhibitors and appetite suppressants.
Less common, yet serious adverse effects include suicidal thoughts (SSRIs), hyponatremia (SSRIs), Serotonin syndrome (SSRIs), cardiac arrhythmias/arrest (TCAs), tyramine hypertensive crisis (MAOIs). Fortunately, TCAs and MAOIs are rarely prescribed for anxiety, given the serious side effects of cardiac effects with TCAs and dietary restrictions and drug-drug interactions with MAOIs. In addition, overdosing on TCAs is usually fatal.
In summary, while prescription medications can be effective for anxiety, they may also have side effects which range from mild (a nuisance) to serious (life-threatening). Psychiatrists are fortunate to have a range of prescription medication options for anxiety. However, psychiatrists spend much time with patients managing the side effects that emerge during prescription anxiety medication treatment, and this list is a compact summary of those potential side effects.