A selective serotonin reuptake inhibitor (SSRI) is a type of antidepressant. It is commonly prescribed for various conditions such as anxiety and depression as it is relatively safe and have fewer side effects than other antidepressants.

This article details more about SSRIS, how they work, conditions they treat, their types, and much more, to help you understand if it is the right choice for you.

What Does SSRI Mean?

Imagine your dog is sick or your favorite sports team is losing. You may feel sad, right? It’s okay to feel sad from time to time. But this is not the case with someone who is depressed.

People with depression have feelings of sadness that prevent them from doing their daily activities. It may be hard for them to function at work or home, and these feelings can lead to multiple emotional and physical problems.

That is because brain chemicals responsible for making you feel good or happy, such as serotonin and dopamine, are abnormal in people with this condition.

Serotonin supplies cells related to mood, social behavior, appetite, sexual desire and function, learning and memory, and temperature regulation. Low levels of serotonin are associated with depression, sexual problems, and other disorders.

SSRIs inhibit the reuptake or reabsorption of serotonin into nerve cells. This increases its level in the brain and improves the transmission of messages between these cells. As these drugs affect mainly serotonin and no other neurotransmitters, they are called selective.

How Do SSRIs Work?

Different nerve cells have different functions. SSRIs enhance the functioning of nerve cells that regulate your emotions. These cells transmit the information as signals between your brain cells. The chemical messengers that aid in the transmission of these signals are known as neurotransmitters.

Here is how this spread occurs:

When the brain cells pass signals to one another, they also release the chemicals to deliver the message. They have to take back the chemical so that they can pass the next message. This process of taking the chemical back is known as “reuptake.”

If you are suffering from depression, the brain areas that regulate mood are not working efficiently. 

SSRIs work by inhibiting the reuptake, allowing its level to increase in the blood. This ultimately allows the message to be sent correctly. As this medicine targets only serotonin, they’re called “selective” serotonin reuptake inhibitors.

So, SSRIs do not cause your body to make more serotonin but helps it to use what is there more effectively.

Conditions SSRIs Can Treat

Along with depression, SSRIs can also help manage the following conditions:

  • Panic disorder
  • Post-traumatic stress disorder
  • Hot flashes caused by menopause
  • Obsessive-compulsive disorder
  • Bulimia
  • Premenstrual dysphoric disorder (PMDD)
  • Anxiety

Different Types of SSRI Medications 

Here are some common types of SSRIs available in Canada:


Selective serotonin reuptake inhibitors (SSRIs) and serotonin and norepinephrine reuptake inhibitors (SNRIs) are different types of antidepressant medications. 

As the name suggests, SSRIs increase only the amount of serotonin in the brain, while SNRIs increase serotonin and norepinephrine levels.

When we talked about neurotransmitters before, we learned that they aid in passing signals. These signals can be of two types, excitatory and inhibitory. Excitatory neurotransmitters excite a nerve signal while inhibitory neurotransmitters weaken them. Serotonin can serve both roles, while norepinephrine is purely excitatory. 

Now, talking about the difference between SSRIs and SNRIs:

  • SSRIs block the reuptake of only serotonin
  • SNRIS block the reuptake of both serotonin and norepinephrine

Serotonin mainly regulates your mood, and norepinephrine aids in the fight-or-flight reaction. So, SSRIs aid in improving mood and depression, and SNRIs help you concentrate and reduce depression.

There is no evidence that either group of drugs is superior to the other. Different individuals respond differently to medicines.

Both classes of drugs can take several weeks to work.

Common Side Effects Of SSRI 

SSRIs are relatively safe, but they are not effective for everyone. For instance, it is not suitable if you are pregnant or under 18 years as it increases the risk of side effects.

The medicine should also be used with caution in the presence of certain disorders like epilepsy, diabetes, and kidney disorders. Besides, some SSRIs also interact with other medicines, including herbal supplements, over-the-counter medications, and painkillers.

Side Effects

Common side effects

  • Dry mouth
  • Trouble sleeping
  • Diarrhea or constipation
  • Increased sweating
  • Nervousness
  • Nausea
  • Headache
  • Tiredness
  • Increased sweating
  • Weight gain or weight loss
  • Change in appetite
  • Sexual dysfunction, including a low sex drive
  • Difficulty in reaching orgasm during masturbation or sex
  • Erectile dysfunction in men
  • Rash
  • Nervousness
  • Indigestion
  • Blurred vision

Less common side effects

  • Confusion
  • Hallucinations, a condition where you see or hear things that are not in real
  • Bleeding or bruising easily
  • Blood in stool or vomit
  • Being unable to pee

So, if you have symptoms or any condition, it is best to consult your doctor or pharmacist. They will help you know if SSRIs are a better option for you.

Safety Issues

SSRIs are usually safe but may cause concerns in some cases. For instance, high doses of citalopram may cause dangerous abnormal heart rhythms. So, according to FDA, doses above 40 mg should be avoided.

The medicine should be taken with caution in the following conditions:

  • Bleeding disorder such as hemophilia
  • Bipolar disorder
  • Epilepsy
  • Diabetes
  • Severe liver, kidney, or heart problems
  • Narrow-angle glaucoma
  • Pregnancy and lactation

SSRIs can cause blurred vision, dizziness, and drowsiness, making it difficult to drive or operate machinery.

It is also not recommended to take alcohol and SSRIs as they may worsen drowsiness, making depression worse.

Serotonin Syndrome

In rare cases, SSRIs can result in high serotonin levels. It usually occurs when two medicines increasing serotonin levels are combined. For instance, taking them with other antidepressants or headache medicines.

Some symptoms of serotonin syndrome include:

  • Agitation
  • Sweating
  • Tremors
  • Lack of coordination
  • Rapid heart rate
  • Anxiety
  • High fever
  • Confusion
  • Restlessness
  • Change in blood pressure

If you have any of the mentioned side effects, it is best to seek medical help immediately. 

Suicidal Risk

Most SSRIs are safe, but FDA requires that they carry warnings on the box and the strictest warnings for the prescription. In some cases, young adults under 25 and teens are seen to have an increase in suicidal behavior or thoughts after taking SSRIs, especially in the first few weeks of taking them.

So, anyone taking SSRI is watched closely for unusual behavior or worsening depression.

However, it should be kept in mind that SSRIs lower the risk of suicide in the long run.

Dosage and Prescription

SSRIs are supposed to be taken in tablet form. When prescribed, it will be given in the possible lowest dose.

Your doctor will usually start with a 20-40 mg dose, and it may take 2-4 weeks before you can see any benefit. It may also be possible that you may face side effects. But do not stop taking it without consulting your doctor. These effects wear off quickly.

However, if four to six weeks go without any improvement, you can speak to your doctor. They may advise a change in dose or an alternative antidepressant.

The course usually lasts for at least six months. But more extended treatment might be needed in some cases

Stopping Treatment

Although SSRIs are not habit-forming, they need to be stopped or lowered their dose gradually. Failing to do so may result in sudden low serotonin levels preventing your brain from adapting to those levels. This is known as discontinuation syndrome that may cause withdrawal-like symptoms.

Some common symptoms include:

  • Dizziness
  • Lethargy or fatigue
  • Nausea
  • Uneasiness
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