Celebrex (Celecoxib)

How does it work?

Celebrex capsules contain the active ingredient celecoxib, which is a type of medicine known as a non-steroidal anti-inflammatory drug (NSAID).

NSAIDs work by blocking the action of a substance in the body called cyclo-oxygenase. Cyclo-oxygenase is involved in producing prostaglandins, in response to injury or certain diseases. These prostaglandins cause pain, swelling and inflammation. Because NSAIDs block the production of these prostaglandins, they are effective at relieving pain and inflammation.

Cyclo-oxygenase does not only produce prostaglandins that cause inflammation. It also produces prostaglandins that have useful roles in the body. There are two different forms of cyclo-oxygenase, COX-1 and COX-2. COX-2 is the form that (among other things) produces prostaglandins that cause inflammation. COX-1 does not produce inflammatory prostaglandins, but does produce others that have useful effects, including some that are involved in maintaining a healthy stomach and intestinal lining.

Traditional NSAIDs, such as ibuprofen or diclofenac, block the action of both COX-1 and COX-2, and this is why they can sometimes cause side effects such as stomach irritation and peptic ulcers. Celecoxib belongs to a new generation of NSAIDs that selectively block the action of COX-2. This means that it stops the production of inflammatory prostaglandins, without stopping the production of prostaglandins that protect the stomach and intestines. It therefore reduces pain and inflammation, but is less likely than traditional NSAIDs to cause side effects on the stomach and intestines (although such side effects are still possible).

What is it used for?

  • Rheumatoid arthritis.
  • Osteoarthritis.
  • A form of arthritis affecting the joints of the spine (ankylosing spondylitis).


  • This medicine may cause dizziness or sleepiness and so may affect your ability to drive or operate machinery safely. Do not drive or operate machinery until you know how this medicine affects you and you are sure it won't affect your performance.
  • This medicine may hide a fever, which is a sign of infection. This may make you think mistakenly that an infection is getting better when it isn't, or that an infection is less serious than it is. For this reason you should tell your doctor if you get an infection while you are taking this medicine.
  • Your doctor will prescribe you the lowest effective dose of this medicine for the shortest possible time necessary to relieve your symptoms. This is to minimise the chances of any side effects, particularly those mentioned below. It is important not to exceed the prescribed dose.
  • NSAIDs can occasionally cause serious side effects on the gut, such as ulceration, bleeding or perforation of the stomach or intestinal lining. This type of side effect is more likely to occur in elderly people and in people taking high doses of the medicine. The risk can also be increased by taking certain other medicines (see below). It is important that these people, as well as people with a history of disorders affecting the stomach or intestines, are closely monitored by a doctor while taking this medicine. All people taking this medicine should stop treatment and consult their doctor immediately if they experience any sign of bleeding from the stomach or intestine during treatment, for example vomiting blood and/or passing black/tarry/bloodstained stools.
  • COX-2 inhibitors may carry an increased risk of heart attacks and stroke when compared to placebo (no treatment). If you have risk factors for heart disease or stroke, such as diabetes, high cholesterol or smoking, your doctor will need to assess the overall benefits and risks before deciding if this medicine is suitable for you. In general, if this medicine is suitable, your doctor will prescribe the lowest effective dose for as short a time as possible to control your symptoms, because the risks may increase with higher doses and the longer the medicine is taken. Do not exceed the prescribed dose. Tell your doctor if you experience shortness of breath, chest pains or ankle swelling while taking the medicine. Ask your doctor or pharmacist for further information.
  • It is recommended that your blood pressure is regularly monitored while you are taking this medicine.
  • If you have any existing problems with your kidneys, liver or heart function, your kidney function should be regularly monitored while you are taking this medicine.
  • Some cases of severe liver reactions have been reported in people taking this medicine. Most of these developed within one month of starting treatment. For this reason, while you are taking this medicine you should let your doctor know straight away if you notice any symptoms that could indicate a problem with your liver. These may include yellowing of the skin or whites of the eyes (jaundice), unusually dark urine, nausea and vomiting, loss of appetite or flu-like symptoms.
  • Very rarely, NSAIDS may cause serious blistering or peeling skin reactions (eg Stevens-Johnson syndrome, toxic epidermal necrolysis, exfoliative dermatitis). For this reason, you should stop taking this medicine and consult your doctor if you get a skin rash or sores inside your mouth while taking this medicine. This side effect is very rare, but if it occurs, is most likely to happen in the first month of treatment.

Use with caution in

  • Elderly people.
  • Decreased liver function.
  • Decreased kidney function.
  • People with a decreased volume of fluid in the body, eg due to dehydration, high doses of diuretics, severe vomiting or diarrhoea.
  • History of heart failure.
  • Swelling due to excess fluid retention (oedema).
  • History of disorders affecting the stomach or intestines, such as ulceration or bleeding.
  • High blood pressure (hypertension).
  • Raised levels of fats such as cholesterol in the blood (hyperlipidaemia).
  • Diabetes.
  • Smokers.
  • People who may be poor metabolisers of this medicine, due to reduced activity of an enzyme in the liver known as CYP2C9 (your doctor may be aware of this based on your previous response to certain other medicines).
  • People with a history of allergic reactions to medicines.

Not to be used in

  • Children.
  • Allergy to medicines from the sulphonamide group, eg the antibiotic sulfamethoxazole.
  • People in whom aspirin or other NSAIDs, eg ibuprofen, cause allergic reactions such as asthma attacks, itchy rash (urticaria), nasal polyps, nasal inflammation (rhinitis) or swelling of the lips, tongue and throat (angioedema).
  • People with an active peptic ulcer or bleeding from the gut.
  • Inflammatory bowel disease such as Crohn's disease or ulcerative colitis.
  • Severe liver disease.
  • Moderate to severely decreased kidney function.
  • Heart failure.
  • Heart disease caused by inadequate blood flow to the heart (ischaemic heart disease), eg angina or history of heart attack.
  • Disease of the blood vessels in and around the brain (cerebrovascular disease), eg history of stroke.
  • Poor circulation in the arteries of the legs or feet (peripheral arterial disease).
  • Pregnancy.
  • Breastfeeding.
  • Rare hereditary problems of galactose intolerance, the Lapp lactose deficiency or glucose-galactose malabsorption (Celebrex capsules contain lactose).

This medicine should not be used if you are allergic to one or any of its ingredients. Please inform your doctor or pharmacist if you have previously experienced such an allergy.If you feel you have experienced an allergic reaction, stop using this medicine and inform your doctor or pharmacist immediately.

Pregnancy and breastfeeding

Certain medicines should not be used during pregnancy or breastfeeding. However, other medicines may be safely used in pregnancy or breastfeeding providing the benefits to the mother outweigh the risks to the unborn baby. Always inform your doctor if you are pregnant or planning a pregnancy, before using any medicine.

  • This medicine should not be used during pregnancy, particularly during the third trimester, as it may be harmful to an unborn baby. Women who could get pregnant should use an effective method of contraception to avoid pregnancy while taking this medicine. If you think you could be pregnant, stop taking this medicine and consult your doctor immediately. Seek further medical advice from your doctor.
  • This medicine may pass into breast milk. Mothers who need to take this medicine should not breastfeed. Seek further medical advice from your doctor.

Side effects

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 this medicine. Just because a side effect is stated here does not mean that all people using this medicine will experience that or any side effect.

Common (affect between 1 in 10 and 1 in 100 people)

  • Disturbances of the gut such as indigestion, diarrhoea, wind or abdominal pain.
  • Retention of water in the body tissues (fluid retention) causing swelling, particularly of the legs and ankles (peripheral oedema).
  • Inflammation of the sinuses (sinusitis).
  • Inflammation of the throat (pharyngitis).
  • Inflammation of the lining of the nose (rhinitis) causing a blocked or runny nose.
  • Flu-like symptoms.
  • Urinary tract infections.
  • Difficulty sleeping (insomnia).
  • Dizziness.
  • Cough.
  • Skin reactions such as rash or itching.
  • Muscle stiffness.

Uncommon (affect between 1 in 100 and 1 in 1000 people)

  • Anaemia.
  • Tiredness.
  • Anxiety.
  • Depression.
  • Blurred vision.
  • Increased potassium level in the blood (hyperkalaemia).
  • Pins and needles sensations (paraesthesia).
  • Sensation of ringing or other noise in the ears (tinnitus).
  • Awareness of your heartbeat (palpitations) or increased heart rate (tachycardia).
  • Heart failure.
  • Worsening of existing high blood pressure.
  • Constipation.
  • Inflammation of the stomach (gastritis).
  • Abnormal liver or kidney function.
  • Leg cramps.

Rare (affect between 1 in 1000 and 1 in 10,000 people)

  • Ulceration in the stomach or intestines.
  • Inflammation of the pancreas (pancreatitis).
  • Decreased numbers of white blood cells or platelets in the blood.
  • Confusion.
  • Taste disturbances.
  • Unsteady walk.
  • Hair loss.
  • Increased sensitivity of the skin to sunlight.

Frequency not known (reported since the medicine has been on the market, generally considered to be very rare, ie affecting less than 1 in 10,000 people)

  • Bleeding (haemorrhage) in the stomach or intestines.
  • Liver failure or inflammation (hepatitis).
  • Kidney failure.
  • Severe skin reactions.
  • Severe allergic reactions.
  • Aggravation of epilepsy.

Increased blood pressure, shortness of breath, heart attack and stroke have also been reported with this medicine in clinical trials involving people taking high doses (400mg daily) for long periods of time (up to three years).

The side effects listed above may not include all of the side effects reported by the medicine's manufacturer.For more information about any other possible risks associated with this medicine, please read the information provided with the medicine or consult your doctor or pharmacist.

How can this medicine affect other medicines?

It is important to tell your doctor or pharmacist what medicines you are already taking, including those bought without a prescription and herbal medicines, before you start treatment with this medicine. Similarly, check with your doctor or pharmacist before taking any new medicines while taking this one, to ensure that the combination is safe.

Celecoxib may be taken with low-dose (75mg daily) aspirin. However, the combination may carry an increased risk of ulceration or bleeding in the stomach or intestines compared to taking celecoxib on its own. Celecoxib should not be taken with higher daily doses of aspirin. For more information and advice ask your doctor or pharmacist.

This medicine should not be taken with other non-steroidal anti-inflammatory drugs (NSAIDs), eg ibuprofen, diclofenac, as using more than one NSAID together may also increase the risk of side effects on the gut.

There may be an increased risk of bleeding if celecoxib is taken by people taking anti-blood-clotting medicines (anticoagulants) such as warfarin. If you are taking an anticoagulant you should have your blood clotting time (INR) monitored while taking celecoxib, particularly in the first few days after starting treatment, or if your dose is changed.

This medicine may oppose the effect of diuretics and medicines for high blood pressure (antihypertensives).

There may be an increased risk of side effects on the kidney if celecoxib is taken with any of the following medicines. Your kidney function should be monitored if you are taking any of these medicines in combination with celecoxib, particularly if you are elderly:

  • ACE inhibitors, eg enalapril
  • angiotensin II antagonists, eg losartan
  • ciclosporin
  • diuretics, eg bendroflumethiazide, furosemide
  • tacrolimus.

Celecoxib may increase the blood level of the mood stabilising medicine lithium. If you are taking lithium, your lithium blood level should be monitored when starting, changing dose, or stopping treatment with celecoxib.

Other NSAIDs can reduce the removal of the medicine methotrexate from the body. This has not been reported with celecoxib, but people taking methotrexate should be monitored for any side effects of methotrexate while taking celecoxib.

There is a possibility that celecoxib may increase the blood levels of the following medicines:

  • dextromethorphan
  • antidepressants (tricyclics, eg amitriptyline and SSRIs, eg fluoxetine)
  • antipsychotic medicines (eg haloperidol)
  • anti-arrhythmic medicines (eg flecainide).

The antifungal medicine fluconazole may increase the blood level of celecoxib. Your dose of celecoxib should be halved if you also take fluconazole. Ask your pharmacist for further advice.

There is a possibility that the following medicines may reduce the blood level of celecoxib:

  • rifampicin
  • carbamazepine
  • barbiturates.

Other medicines containing the same active ingredient

There are currently no other medicines available in the UK that contain celecoxib as the active ingredient.