HeadMeds gives young people in the United Kingdom general information about medication. HeadMeds does not give you medical advice. Please talk to your Doctor or anyone else who is supporting you about your own situation because everyone is different. Please read more important details about our site.

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Duloxetine

Return to Duloxetine overview
  1. Use and Action
  2. Warnings and side effects
  3. Sex, drink, weight and everything else

If you have any thoughts of suicide, or of other ways of hurting yourself, go straight to a hospital with your medicine. This may be a side-effect, and you need urgent help.

Duloxetine can make some people think about hurting themselves or have suicidal thoughts. This can happen to anyone, especially people who are under 18.

You must go straight to hospital with your medicine if you have any of these thoughts. You must tell the doctor that you are taking duloxetine. There are other things you can take instead.

This can happen just after you stop taking duloxetine as well, so please tell the doctor about duloxetine - even if you have just stopped taking it.

Duloxetine has some side effects, and if they happen they can be serious

Stop taking duloxetine and go to a doctor or hospital straight away if you get any of the following symptoms:

  • Difficulty breathing, any rash and itching, or swelling of your face, lips, tongue or throat so that you cannot swallow or breathe.
  • This might be an allergic reaction. 

Go to a doctor or hospital straight away, but do not stop your duloxetine, if you get any of the following symptoms:

  • You get a high temperature/fever, agitation, confusion, trembling or weird muscle movements. These may be signs of a rare condition called ‘serotonin syndrome’.
  • Tiredness, confusion and muscle twitching. You may have a low blood level of sodium.
  • Your skin starts going red and blistering or peeling.

  • Unexplained vaginal bleeding (like an unusual period for girls).

The capsules contain gelatin, sugar and some additives that can cause allergic reactions in some people

  • The capsules contain gelatin, which some people do not like to eat because of religious or cultural beliefs.
  • The capsules contain a small amount of sugar (sucrose and sugar spheres).

Tell your doctor or pharmacist before you take duloxetine if you have, or have ever had, any of these conditions

You need to talk to your doctor or pharmacist before you take duloxetine if you have, or have ever had:

  • eye problems, such as certain kinds of glaucoma (increased pressure in the eye)
  • low sodium levels in your blood, seen in tests (hyponatraemia)
  • a tendency to develop bruises or to bleed easily (bleeding disorders)
  • mania (feeling over-excited or unusually happy)
  • bipolar disorder (feeling over-excited or extremely happy, and then sometimes feeling very low)
  • kidney or liver problems
  • heart problems
  • fits (seizures, epilepsy)
  • thoughts of harming or killing yourself
  • an allergy to duloxetine or other ingredients in tablets and capsules

Some side-effects that do appear should get better after a few days. If they do not, you should go back to your doctor. If you get any side effects not listed here please look at the patient leaflet in the medicine pack

Some side-effects of duloxetine may - strangely - seem like other mental health symptoms. Some side-effects here are also the opposites of each other. The balance of chemicals in the brain is very fragile, and hard to control! If they do not get better after a few days on the tablets, go back to the doctor. 

Do not stop taking the tablets until you talk to your doctor, or you may get withdrawal symptoms as well. 

Very common side effects (could affect more than 1 in 10 people)

  • Headache
  • Feeling sleepy
  • Feeling sick (nausea)
  • Dry mouth 

Common side effects (could affect up to 1 in 10 people)

  • not feeling hungry
  • weight loss - Some children and young people aged under 18 who took duloxetine had some weight loss at first, but after 6 months of treatment they went back to normal compared with other people of the same age
  • feeling nervous, anxious, restless, agitated or tense
  • lower sex drive, or other sexual problems including difficulty staying hard (keeping your erection) in men to have sex, and difficulty having an orgasm (coming)
  • sleep problems, unusual dreams, tiredness or sleepiness
  • feeling dizzy
  • feeling sluggish - having low energy
  • uncontrollable shaking movements, or feeling numb
  • blurred eyesight
  • feeling your pumping heartbeat in your chest, higher blood pressure
  • flushing red skin, sweating more
  • yawning a lot
  • ringing in the ears (tinnitus)
  • indigestion, being sick, constipation or diarrhoea, stomach pain, or farting
  • itchy skin rash, or skin prickling/tingling/numbness
  • muscle pain or spasm
  • going to wee more often, which may be painful
  • falling (this happens mainly in older people) 
  • There are other side-effects that you can get when taking this medicine - we have only included the most common ones here.
  • Please look at the paper leaflet inside your medicine box, or ask a doctor or pharmacist, if you want to know if you are getting a side-effect from your medicine.
  • If you do get a side-effect, please think about reporting it to the Yellow Card Scheme.  

Duloxetine does not mix well with some other medicines and drugs

Do not take duloxetine if you take:

  • An antidepressant medicine called a monoamine oxidase inhibitor (MAOI), or if you have taken one in the last two weeks
  • Fluvoxamine to treat depression
  • Ciprofloxacin or enoxacin, which are antibiotics
  • Any other medicine containing duloxetine. 

Talk to your doctor or pharmacist if you are taking any of the following medicines:

  • other antidepressant medicines including citalopram, sertraline, paroxetine, fluoxetine, or the herbal medicine St John’s Wort – if these are taken together with duloxetine, it could increase your risk of developing serotonin syndrome
  • other mental health medicines that affect serotonin levels including lithium, tryptophan, and tricyclic antidepressants (like imipramine, desipramine and amitriptyline)
  • the painkillers tramadol, pethidine and triptans (for migraine), which affect serotonin levels
  • medicines that can cause sleepiness, including benzodiazepines, strong painkillers, antipsychotics, phenobarbital and antihistamines
  • any medicine that can cause liver problems (ask your doctor or pharmacist to check this for your medicines)
  • warfarin, anti-inflammatory painkillers like ibuprofen, or other medicines which can thin the blood (like clozapine and aspirin), which can increase the risk of bleeding.

Always talk to the doctor if you are taking other medicines. Tell the pharmacist you are taking duloxetine if you buy medicines (including things you put on your skin) for common illnesses.

Be careful if you are also using street drugs

We do not know how duloxetine mixes with street drugs, but it is likely to be similar to the antidepressant fluoxetine:

  • Cannabis can make drowsiness worse with fluoxetine and give you a fast heartbeat.
  • Methadone can make sleepiness worse with fluoxetine. The fluoxetine could increase the concentration of methadone in your body.
  • Fluoxetine could raise the level of cocaine in your body, giving you a bigger reaction.
  • Taking fluoxetine with cocaine or ecstasy or amphetamines could bring on serotonin syndrome. You could get a high temperature/fever, agitation, confusion, trembling or weird muscle movements. You need to go to hospital if this happens. Tell the doctor everything that you have taken.

Stopping this medicine quickly, or reducing the dose too much at once, may cause uncomfortable symptoms. You can stop taking it safely with your doctor’s help

Once you start taking a medicine like duloxetine, the brain adjusts to having a new level of serotonin around. If you stop taking duloxetine all at once, the balance starts to change again. You could get some symptoms from the change.

You may get uncomfortable withdrawal symptoms if you stop duloxetine suddenly. It is better to agree stopping with a doctor who will reduce your dose gradually over at least 2 weeks.

Some of the symptoms you might get include

  • dizziness
  • headaches
  • tingling feelings like pins and needles, or electric shocks (particularly in the head)
  • sleep disturbances (vivid dreams, nightmares, not being able to sleep)
  • feeling anxious, restless, agitated or irritable
  • feeling sick or being sick
  • shaking
  • feeling unusually tired or weary
  • muscle pain
  • diarrhoea (loose poo)
  • sweating a lot
  • vertigo (losing your balance)
  • These symptoms should stop after 2 weeks for most people, but some people can get them for 2-3 months or more.
  • Most people get mild symptoms, but for some people they can be very intense.
  • Go and speak to your doctor if you have missed a few doses, or have decided to stop taking your medication.
  • When you agree with your doctor to stop the medicine, you will carry on with a lower dose for at least 2 weeks. This will lower your risk of getting withdrawal symptoms.

Reference sources

Cymbalta SPC 4.4 last updated 8 Feb 2017
https://www.medicines.org.uk/emc/medicine/15694 Accessed 21/02/2017

Cymbalta SPC 4.7 last updated 8 Feb 2017
https://www.medicines.org.uk/emc/medicine/15694 Accessed 21/02/2017

Cymbalta SPC 4.8 last updated 8 Feb 2017
https://www.medicines.org.uk/emc/medicine/15694 Accessed 21/02/2017

Cymbalta PIL 2 last updated January 2017
https://www.medicines.org.uk/emc/PIL.15601.latest.pdf Accessed 21/02/2017

Cymbalta PIL 3 last updated January 2017
https://www.medicines.org.uk/emc/PIL.15601.latest.pdf Accessed 21/02/2017

Cymbalta PIL 4 last updated January 2017
https://www.medicines.org.uk/emc/PIL.15601.latest.pdf Accessed 21/02/2017

Neal MC. Medical Pharmacology at a Glance (7th Edition). Oxford: John Wiley & Sons, 2012. P63

Maudsley 12th ed p473.

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