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Selective serotonin reuptake inhibitors - Cautions and interactions

Selective serotonin reuptake inhibitors (SSRIs) are not suitable for everyone as they can cause problems if you have other health conditions or if they are 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, are described below.

Medical conditions

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

  • bipolar disorder and you are in a manic phase (a period of extremely excitable moods), although they can be useful for depressive phases
  • a bleeding disorder, such as haemophilia
  • type 1 or type 2 diabetes
  • epilepsy – SSRIs should only be taken if your epilepsy is well controlled, and the medication should be stopped if your epilepsy gets worse
  • narrow angle glaucoma (increased pressure in the eye)
  • 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.


As a precaution, SSRIs are not usually recommended during pregnancy, especially during the first three 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

However, it is not clear whether SSRIs do definitely cause these complications. Most experts think that if SSRIs do increase risks of complications in pregnancy, the increase is probably small.

If you are pregnant and think you may be depressed, you should discuss risks and benefits of using SSRIs with your doctor. If SSRIs are recommended, you will 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 are taking SSRIs.


As a precaution, SSRIs are not usually recommended if you are breastfeeding. This is because the medication may be passed to your baby in your breast milk.

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

If you are prescribed SSRIs when breastfeeding, paroxetine or sertraline are normally recommended.

Children and young people

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

Concerns have also been raised that 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) alone have not helped. In these 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 experience these problems, you should avoid driving or using tools and machinery.

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'. Read about the side effects of SSRIs for more information.

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

However, this is not 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 (PIL) that comes with your SSRI medication to see if there are any medications you should avoid. Online versions of most PILs can be found in the medicines A-Z.

If in doubt, your pharmacist or GP should be able to advise you.

Interactions with food and drink

Alcohol is not usually recommended if you are taking an SSRI as 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.

Therefore, you should 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 is evidence of its effectiveness, 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.

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