Selective serotonin reuptake inhibitors (SSRIs)Cautions

Selective serotonin reuptake inhibitors (SSRIs) aren't suitable for everyone. They can cause problems if you have other health conditions or if they're taken alongside other medications.

Some of the issues you and your doctor will need to bear in mind when taking SSRIs, or when considering using them, include:

Medical conditions

SSRIs may not be suitable if you have any of the following conditions:

• bipolar disorder and you're in a manic phase (a period of extremely excitable mood), although they can be useful for depressive phases
• a bleeding disorder, such as haemophilia
• type 1 diabetes or type 2 diabetes
• epilepsy – SSRIs should only be taken if your epilepsy is well controlled, and they should be stopped if your epilepsy gets worse
• narrow angle glaucoma
• serious kidney, liver or heart problems

SSRIs may need to be used with caution or not at all if you have one of these conditions, because the medication could increase your chance of experiencing serious side effects.

Pregnancy

If you're pregnant and think you may be depressed, you should discuss the risks and benefits of using SSRIs with your doctor. If SSRIs are recommended, you'll usually be prescribed fluoxetine, citalopram or sertraline because these are thought to be relatively safe to use.

You should also speak to your doctor for advice if you become pregnant while you're taking SSRIs.

As a precaution, SSRIs aren't usually recommended during pregnancy, particularly during the first 3 months (the first trimester). This is because there may be a risk to the baby.

However, exceptions can be made if the risk posed by depression (or another mental health condition) outweighs the potential risks of treatment.

Possible risks of taking SSRIs during pregnancy include:

• loss of the pregnancy
• birth defects affecting the baby’s heart (congenital heart disease)
• the baby being born with a rare condition called persistent pulmonary hypertension in the newborn (PPHN), which causes breathing and circulation problems

Breastfeeding

If you're prescribed SSRIs when breastfeeding, paroxetine or sertraline are usually recommended and are considered safe to use.

However, other SSRIs may be used if it's thought that the benefits of treatment and benefits of breastfeeding your baby outweigh the potential risks.

Children and young people

SSRIs aren't usually recommended for children and young people under the age of 18. This is because there's evidence of an increased risk of self-harm and thoughts about suicide in this age group.

There are also concerns that the use of SSRIs could affect brain development in children and young people.

However, children and young people under the age of 18 may be offered an SSRI if talking therapies, such as cognitive behavioural therapy (CBT), alone haven't helped. In such cases, an SSRI will only be prescribed in addition to a talking therapy and treatment must be supervised by a psychiatrist (a doctor who specialises in treating mental health conditions).

If an SSRI is recommended, fluoxetine is usually the first choice.

Driving and operating machinery

Some SSRIs can cause dizziness, drowsiness and blurred vision, particularly when you first start taking them.

If you do experience these symptoms, you shouldn't drive or use heavy tools and machinery. The symptoms should be temporary, but speak to your doctor if you're unsure.

Interactions with other medications

SSRIs can react unpredictably with certain other medications (known as "interacting"), potentially increasing the risk of side effects such as bleeding or a problem known as "serotonin syndrome".

Some of the medications that can interact with some SSRIs include:

• non-steroidal anti-inflammatory drugs (NSAIDs) – a common type of painkiller that includes ibuprofen, diclofenac or naproxen
• antiplatelets – a type of medication used to prevent blood clots, such as low-dose aspirin and clopidogrel
• theophylline – a medication used to treat asthma
• clozapine and pimozide – medications used to treat schizophrenia and psychosis
• lithium – a medication used to treat severe depression and bipolar disorder
• triptans – a type of medication, such as naratriptan, sumatriptan and zolmitriptan, used to treat migraines 
• other antidepressants – including tricyclic antidepressants (TCAs), monoamine oxidase inhibitors (MAOIs) and serotonin-norepinephrine reuptake inhibitors (SNRIs)

However, this isn't an exhaustive list of all the medications that can interact with SSRIs, and not all of these interactions apply to all types of SSRI.

You should always make sure you carefully read the patient information leaflet that comes with your SSRI medication to see if there are any medications you should avoid. If in doubt, your pharmacist or GP should be able to advise you.

Interactions with food and drink

Alcohol isn't usually recommended if you're taking an SSRI, because it can increase any drowsiness you may experience and can make feelings of depression worse.

The SSRI, fluvoxamine, is also known to enhance the effects of caffeine, so people who drink large amounts of caffeine may experience unpleasant symptoms such as palpitations, feeling sick, restlessness and insomnia.

You should therefore avoid drinking large amounts of caffeinated drinks, such as tea, coffee, energy drinks and cola, while taking fluvoxamine.

St John's wort

St John's wort is a popular herbal remedy promoted for the treatment of depression.

While there's some evidence that St John's wort may help mild to moderate depression, many experts advise against using it because the amount of active ingredient can vary significantly and you can never be sure what sort of effect it will have on you.

Taking St John's wort alongside SSRIs can also potentially cause serious health problems.