Antidepressant medications treat depression. Currently, the most popular antidepres-sants are the serotonin repuptake inhibitors (SSRIs), which work on the serotonin neurotransmitter system. Commonly prescribed SSRIs include fluoxetine (Prozac), sertraline (Zoloft), citalopram (Celexa), and paroxetine (Paxil). SSRIs are very effective and safer than other classes of antidepressants but they do have side effects, the most bothersome being sexual side effects. SSRIs are also helpful in the treatment of anxiety conditions and obsessive-compulsive disorder.

Prior to the arrival of the SSRIs in the 1980s, heterocyclics were the most frequently prescribed class of antidepressants. Commonly used heterocyclics include imipramine (Tofranil), amitriptyline (Elavil), and nortriptyline (Pamelor). Hetero-cyclics, which get their name from the ring structure of the drugs’ molecules, hit both the serotonin and norepinephrine neurotransmitter systems, with an emphasis on norepinephrine. They also impact the histaminic and and acetylcholine neurotransmitter systems. Heterocyclics have more dangerous side effects than SSRIs. They are more lethal on overdose and can have notable cardiac side effects.

Another class of antidepressants is monoamine oxydase inhibitors (MAOIs). MAOIs were discovered in the early 1950s and their potentially lethal effects came to light in the early 1960s. MAOIs can cause a hypertensive crisis, in which blood pressure shoots up high enough to cause a stroke.

These crises can be brought on by mixing an MAOI with another medication, such as opioids or SSRIs, or by eating tyramine-rich foods. Aged cheese, cured meats, sausage, and liqueurs are all rich in tyramine. Although MAOIs are the most dangerous of the anti-depressants, they are also extremely effective. For those patients with treatment-resistant depression who can follow a low tyramine diet, MAOIs may be a reasonable option. Examples of MAOIs include phenelzine (Nardate) or tranylcypromine (Parnate).