Duloxetine is commonly known by the brand name Cymbalta®. It is one of a group of medicines called the SNRIs (Serotonin and Noradrenaline Reuptake Inhibitors), which are used to improve mood in people who are feeling low or depressed. Antidepressants may also be used to help the symptoms of anxiety and a number of other conditions.
As well as helping to improve mood and treat anxiety duloxetine has also been found to be effective in treating nerve pain, in particular that associated with diabetes.
In June 2008 the USA Food and Drug Administration (FDA) regulators approved duloxetine for the treatment of fibromyalgia and in November 2010 added chronic musculoskeletal pain, including discomfort from osteoarthritis, and chronic lower back pain.
The brain has many naturally occurring chemical messengers. Two of these are called serotonin (also known as 5-HT) and noradrenaline. They are both important in the areas of the brain that control mood and thinking. It is known that these chemicals are not as effective or active as normal in the brain when someone is depressed. Duloxetine increases the amount of these chemical messengers released in the brain. This can help correct the lack of action of these messengers and improve mood.
Duloxetine is also thought to enhance the nerve signals within the central nervous system that naturally inhibit pain.
It may take as long as two weeks or more before duloxetine starts to have any effect, and a further three or four weeks for this effect to be reaching its maximum. It’s therefore important that patients continue to take duloxetine for at least six weeks before any decisions are made about its efficacy.
Duloxetine capsules should be swallowed with at least half a glass of water whilst sitting or standing. This is to make sure that they reach the stomach and do not stick in the throat. They should be swallowed whole.
The recommended dose is 60 mg a day. However, in some cases patients are advised to start on 30 mg a day for the first week, before increasing to the full dose. It is important to keep in mind that there is no evidence to suggest that taking more than 60 mg a day will further reduce pain. In fact, doing so could increase the chance of side effects.
Taking duloxetine with a meal can reduce stomach upsets.
Patients are advised not to drink alcohol when taking duloxetine. Doing so can increase the risk of liver damage.
It is important not to suddenly stop taking duloxetine. Doing so may cause unpleasant side effects, including nausea and headache. A doctor should be consulted for advice on how to slowly reduce the dose.
Medicines and their possible side effects can affect individual people in different ways. The following are some of the side effects that are known to be associated with duloxetine.
Just because a side effect is stated here does not mean that all people using this medicine will experience that or any side effect.
Very common (affect more than 1 in 10 people):
- Feeling sick.
- Dry mouth.
Common (affect between 1 in 10 and 1 in 100 people):
- Decreased appetite and weight loss.
- Difficulty sleeping (insomnia).
- Increased sweating.
- Blurred vision.
- Pins and needles sensations.
- Taste disturbances.
- Awareness of your heartbeat (palpitations).
- Disturbances of the gut, such as abdominal pain, diarrhoea, constipation, indigestion, vomiting, wind.
- Sensation of ringing or other noise in the ears (tinnitus).
- Muscle spasm, pain or tightness.
- Hot flushes.
- Decreased sex drive or impotence (erectile dysfunction).
- Anxiety or agitation.
- Abnormal dreams.
For more information about any other possible risks associated with duloxetine, please read the information provided with the medicine or consult a doctor or pharmacist.
Duloxetine must not be taken at the same time as, or within two weeks of taking a monoamine oxidase inhibitor (MAOI) antidepressant such as phenelzine, tranylcypromine or isocarboxazid. Conversely, an MAOI should not be started until at least five days after stopping duloxetine. This is because using these medicines together can cause a serious and potentially life-threatening interaction.
The antidepressant moclobemide is not recommended for use in combination with duloxetine. Other antidepressants should only be used with caution.
Side effects may be more common if the herbal remedy St John's wort (Hypericum perforatum) is used in combination with duloxetine. This combination is also not recommended.
The following medicines must not be taken in combination with duloxetine, as they increase the blood level of duloxetine and may increase the risk of its side effects:
Duloxetine should not be used at the same time as a medicine called Yentreve, which also contains duloxetine, but is used for urinary incontinence.
The patient information leaflet (PIL) is a leaflet containing specific information about medical conditions, doses and side effects. You can download a copy of the PIL here:
Patient Info Leaflet