Selective Serotonin Reuptake Inhibitors (SSRIs)

Overview

SSRI stands for Selective Serotonin Reuptake inhibitor. This type of drug is most commonly prescribed as an antidepressant and works by increasing the amount of serotonin present in the brain.[1]

Serotonin is one of many neurotransmitters (i.e., chemical messengers) in the brain that carry messages between neurons, the nerve cells of the brain.

SSRIs are effective because they block the reabsorption, also known as the reuptake, of serotonin into the neurons. This process is critical because it then allows more serotonin to be available to transfer messages in the brain.[2]

By blocking the reuptake of serotonin, SSRIs are able to help treat depression.[3]

Some of the most common SSRIs include:

Lexapro (Generic name: escitalopram)
Zoloft (Generic name: sertraline)
Prozac (Generic name: fluoxetine)
Paxil (Generic name: paroxetine)
Celexa (Generic name: citalopram)
Luvox (Generic name: fluvoxamine)
Paxil CR (Generic name: paroxetine)
Brisdelle (Generic name: paroxetine)[4]

Conditions Treated

While the most common use of this type of drug is to treat depression, other conditions that SSRIs can also be used for include:[5]

There are also several “off label” uses of SSRIs, (i.e. other ways this type of drug is effective, even though it was not specifically developed for these conditions) which include aiding in the treatment of:[6]

Fibromyalgia
Binge eating disorder
Body dysmorphic disorder
Autism

How They Work

To understand how SSRIs work, one must first understand how serotonin is processed. Referred to as the “feel-good chemical” in the brain because it can cause one to feel very relaxed[7], serotonin has many positive attributes. These include: regulating the body’s sleep-wake cycle and internal clock; contributing to good moods; spurring healthy appetites, and contributing to general well-being.[8] Normally, this hormone circulates in the brain while carrying messages, and is then absorbed into the blood stream.[9]

Depression has been found to be connected to low levels of certain hormones in the brain such as serotonin, dopamine and norepinephrine;[10] SSRIs work selectively with serotonin.[11] SSRIs do not cause the body to produce more serotonin; they work to make the neurotransmitter more available in the brain’s bloodstream by preventing it from reabsorbed within the brain.[12] With more serotonin available, SSRIs can enhance the neurons in the brain that regulate emotion-leading information to be more easily communicated within the brain.

If someone struggles with depression, the parts of the brain that control mood and send messages via serotonin may not be functioning properly. Increased levels of serotonin circulating between neurons in the brain leads to easier communication of messages/signals within the brain and therefore reduces the prevalence of depression. [13]

Possible Side Effects

For most people, SSRI antidepressants do not have major side effects. However, as with any medical treatment, there are always risks and potential side effects to consider.

Possible side effects of SSRIs include:[14]

Insomnia
Headaches
Rash
Blurred vision
Drowsiness
Dry mouth
Agitation or nervousness
Feeling dizzy
Pain in the joints or muscles
Upset stomach, nausea, or diarrhea
Reduced sexual desire
Problems with erection or ejaculation

While SSRIs generally have the same possible side effects, a person may experience different side effects or to varying degrees since each type of SSRI has a slightly different chemical makeup. If unwanted side effects do occur, it’s important to note that it is not uncommon for these effects to go away after the treatment has continued for a few weeks.

It is important to always work with your doctor, be open and communicate what you are experiencing when taking medication, to find the correct SSRI for you.[15]

Possible Interactions

Although all SSRIs are thought to work similarly, there are slight differences between individual SSRIs concerning how long they remain in the body, how they are metabolized, and how they will potentially interact with other medications.[16]

Since SSRIs can have dangerous interactions with other medications (prescription or over-the-counter), herbs and supplements, it is important to tell your doctor in detail what you are taking before starting a SSRI, and to ask before starting other medications or supplements in the future.[17]

Something to be mindful of is the potential of developing a condition called “serotonin syndrome”, which can happen if too much serotonin builds up in the body. High levels of serotonin can lead to extreme nerve cell activity with dangerous symptoms (i.e. confusion, headache, nausea, high fever, seizures, uneven heartbeat, and passing out).[18] While rare, this condition can occur when two different SSRIs are combined.[19]

Doctor's Guidance

It is always important to work up gradually to your prescribed dosage with guidance from your doctor, and gradually slow down based on your doctor’s recommended treatment plan if and when it is time to stop.[20] While SSRIs are generally not habit-forming, it is still dangerous to stop taking them suddenly or to take them inconsistently. Abruptly halting one’s SSRI intake can lead to a condition known as “discontinuation syndrome”, which causes withdrawal-like symptoms.

Symptoms of discontinuation syndrome include the following flu-like symptoms:[21]

Nausea
Dizziness
Uneasiness
Fatigue or lethargy

If you or someone you know feels they may be experiencing depression, please reach out to a licensed health care provider, such as a primary care physician, psychiatrist or psychotherapist for guidance as soon as possible.

Contributed by: Nikayla Jeffrey