SSRIs

Selective serotonin reuptake inhibitors (SSRIs) are a class of psychiatric drug often prescribed as a first-line treatment to people experiencing symptoms of depression and other mental health problems. SSRIs are more commonly prescribed than other types of psychiatric medication as they are generally better tolerated and have fewer adverse effects.

What are SSRIs used to treat?

SSRIs are a type of antidepressant medication, predominantly prescribed to people experiencing depression. They can also be used to treat other mental health problems such as:

• Obsessive compulsive disorder (OCD)
• Panic disorder
• Generalized anxiety disorder (GAD)
• Post-traumatic stress disorder (PTSD)
• Severe phobias

In addition, SSRIs are sometimes prescribed to help alleviate potential underlying causes of several physical health conditions, such as premenstrual syndrome (PMS), fibromyalgia, and irritable bowel syndrome (IBS). ^[1] Occasionally, they may also be prescribed to treat pain. This isn’t surprising given there is a close link between our physical and mental health, with people who experience chronic or long-term health problems being at greater risk of developing mental health problems. ^[2]

How do SSRIs work?

Experts don’t know exactly how or why SSRIs work in treating depression and other types of mental health problems. We know there is a link between depression and serotonin, a neurotransmitter thought to play a key role in the regulation of our mood, appetite, and sleep.

SSRIs prevent the ‘uptake’ or absorption of serotonin as chemical messages are passed between cells in the brain (‘neurons’). By preventing serotonin being absorbed too quickly, this chemical has longer to act on your brain and body, helping improve mood and potential responsiveness to other treatments such as cognitive behavioral therapy (CBT). ^{[1] [3]}

SSRIs are ‘selective’ because they only target the neurotransmitter serotonin, having little or no effect on other neurotransmitters, such as dopamine or norepinephrine (also known as noradrenaline). But there are other types of antidepressants such as serotonin and noradrenaline reuptake inhibitors (SNRIs) which target more than one neurotransmitter (both serotonin and noradrenaline) – more on this below.

Types of SSRIs

In the US, the SSRIs approved by the Food and Drug Administration (FDA) to be prescribed for depressive disorders and other related mental health problems, such as certain anxiety and eating disorders, include (common brand names in parentheses):

• Fluoxetine (Prozac)
• Sertraline (Zoloft)
• Paroxetine (Paxil)
• Fluvoxamine (Luvox)
• Citalopram (Celexa)
• Escitalopram (Lexapro)
• Vilazodone (Viibryd)

These kinds of SSRIs can also be prescribed for some additional problems ‘off-label’ – at the discretion of the clinician – including binge eating disorder, body dysmorphic disorder, fibromyalgia, premature ejaculation, paraphilias, autism, Raynaud phenomenon, and vasomotor symptoms associated with menopause ^[4].

Side effects of SSRIs

Selective serotonin reuptake inhibitors are generally considered the safest and best tolerated type of antidepressants, ^[5] with fewer side effects than other psychiatric drugs such as monoamine oxidase inhibitors (MAOIs) which are generally only prescribed when other types of drugs have been unsuccessful. ^[6]

That said, there are several potential adverse side effects associated with SSRIs, so do talk to your doctor before deciding if they could be a viable treatment option for you. You will also need to discuss with your clinician what other medications you currently take, if you drink alcohol, and if you are pregnant or planning to become pregnant. ^[7] Most side effects improve over time.

Potential side effects of SSRIs include:

• Sexual problems – including erectile dysfunction, delayed ejaculation,and difficulty reaching orgasm
• Sleep problems
• Weight changes
• Anxiety
• Dizziness
• Tooth decay and dry mouth (‘xerostomia’)
• Headache
• Gastrointestinal pain or bleeding ^{[4] [5]}

Suicidal thoughts and actions

Some research has found an increased risk of suicide attempts among people taking SSRIs when compared to a placebo group. ^[8] However, another piece of research found SSRI treatment does not increase the risk of suicidal behavior in either youths or adults (aged 6-59); rather, it may reduce it. ^[9] 

Although many study findings seem to be contradictory, given the potential severity of this side effect, it’s important that doctors closely monitor patients who have been prescribed SSRIs, particularly those under 25 years old, for whom there is thought to be a greater risk.

Serotonin syndrome

Serotonin syndrome is uncommon but potentially serious. It occurs when the levels of serotonin in your brain become too high. High serotonin levels are usually a result of overdosing on your SSRI or taking your SSRI alongside something else that also raises serotonin levels, such as another antidepressant or St John’s wort.

Symptoms include:

• Confusion
• Agitation
• Sweating
• Shivering
• Muscle twitching
• Diarrhea

If you experience these symptoms, seek immediate advice from your doctor.

Symptoms of severe serotonin syndrome include:

• A high temperature (38C or above)
• Seizures (fits)
• Irregular heartbeat (arrhythmia)
• Loss of consciousness

If you or someone you know experiences symptoms of severe serotonin syndrome, seek emergency medical help immediately by dialling 911. ^[5]

Low salt levels (‘hyponatremia’)

Older people prescribed SSRIs may experience a severe fall in sodium (salt) levels known as hyponatremia. This can lead to a dangerous build-up of fluid inside the body’s cells.

Low salt levels occur because SSRIs can block the effects of a hormone that helps to regulate levels of sodium and fluid in the body. As we get older, fluid levels become more difficult for the body to regulate, which is why older people are worst affected.

Mild hyponatremia can cause symptoms similar to depression or SSRI side effects, including:

• Nausea
• Headache
• Muscle pain
• Loss of appetite
• Confusion

In more severe cases, hyponatremia can cause:

• Feelings of listlessness and tiredness
• Disorientation
• Agitation
• Psychosis
• Seizures (fits)

The most serious cases of hyponatremia can cause patients to stop breathing or go into a coma. Treatment is available by administering sodium into the body through an intravenous (IV) drip. ^[5]

Can you drink alcohol while taking SSRIs?

Ask your doctor or healthcare professional whether it’s safe to drink alcohol with the antidepressant medication you’ve been prescribed, ideally before you start taking them. Alcohol interacts with most antidepressants, including SSRIs. Drinking alcohol while taking antidepressants can:

• Make you feel drowsier than you would from taking the medication alone.
• Affect your ability to perform certain tasks, such as driving.
• Make you more prone to falls and confusion, particularly among older people. ^[7]
• SSRIs are taken orally (by mouth). If you drink so much that you are sick, it can reduce their efficacy.

Coming off SSRIs

Most people continue to take SSRIs for about six months after their symptoms have improved, although some people will stay on them for longer. Some individuals might decide they need to continue taking them indefinitely.

If you decide you want to withdraw from SSRIs, whether that’s because you’re experiencing adverse side effects or because your condition has improved, speak to your doctor. You might find that you experience some withdrawal effects, some of which may be similar to the symptoms of the depression you’re trying to manage, and the side effects of the drug.

Withdrawal effects of SSRIs and SNRIs can include:

• Anxiety and depression
• Depersonalisation (feeling detached from your surroundings)
• Dizziness or vertigo
• Electric shock sensations in head
• Feeling tearful and crying
• Flu-like symptoms
• Gastrointestinal problems, such as stomach cramps
• Mania
• Mood swings
• Motor problems, such as problems with balance, walking, or involuntary movements
• Sensory disturbance, such as smelling something others can’t
• Sleep problems and strange dreams
• Suicidal thoughts
• Tinnitus (ringing in ears)
• Tiredness and weariness
• Trouble with concentration and memory ^[10]

When coming off SSRIs, as with other psychiatric medication, it’s best to gradually reduce your dose, in consultation with your doctor or healthcare professional. Stopping medication suddenly can make withdrawal symptoms worse and can be dangerous. ^[11]