Generic Name: allopurinol (al-oh-PURE-i-nol)
Medically reviewed by Drugs.com. Last updated on Sep 14, 2020.
Commonly used brand name(s)
In the U.S.
Available Dosage Forms:
Therapeutic Class: Antigout
Pharmacologic Class: Xanthine Oxidase Inhibitor
Uses for allopurinol
Allopurinol is used to prevent or lower high uric acid levels in the blood. It is also used to prevent or lower excess uric acid levels caused by cancer medicines or in patients with kidney stones. A high uric acid level can cause gout or gouty arthritis (joint pain and inflammation). Allopurinol is a xanthine oxidase inhibitor that works by decreasing the uric acid produced by the body.
Allopurinol is available only with your doctor's prescription.
Before using allopurinol
In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For allopurinol, the following should be considered:
Tell your doctor if you have ever had any unusual or allergic reaction to allopurinol or any other medicines. Also tell your health care professional if you have any other types of allergies, such as to foods, dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.
Appropriate studies performed to date have not demonstrated pediatric-specific problems that would limit the usefulness of allopurinol in children with high uric acid levels caused by cancer.
No information is available on the relationship of age to the effects of allopurinol in geriatric patients.
There are no adequate studies in women for determining infant risk when using this medication during breastfeeding. Weigh the potential benefits against the potential risks before taking this medication while breastfeeding.
Interactions with medicines
Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking allopurinol, it is especially important that your healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.
Using allopurinol with any of the following medicines is not recommended. Your doctor may decide not to treat you with this medication or change some of the other medicines you take.
Using allopurinol with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.
Using allopurinol with any of the following medicines may cause an increased risk of certain side effects, but using both drugs may be the best treatment for you. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.
- Aluminum Hydroxide
Interactions with food/tobacco/alcohol
Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. Discuss with your healthcare professional the use of your medicine with food, alcohol, or tobacco.
Other medical problems
The presence of other medical problems may affect the use of allopurinol. Make sure you tell your doctor if you have any other medical problems, especially:
- Bone marrow problems or
- Liver disease—Use with caution. May make these conditions worse.
- Cancer (eg, multiple myeloma) or
- Congestive heart disease or
- Diabetes or
- Hypertension (high blood pressure) or
- Hyperuricemia (high uric acid level in the blood) or
- Kidney problems, chronic (eg, glomerulonephritis, pyelonephritis)—Use with caution. May cause side effects to become worse.
- Kidney disease—Use with caution. The effects may be increased because of slower removal of the medicine from the body.
Proper use of allopurinol
Take allopurinol exactly as directed by your doctor. Do not take more of it, do not take it more often, and do not take it for a longer time than your doctor ordered. To do so may increase the chance of side effects.
You may take allopurinol after meals to avoid stomach upset.
Take allopurinol with plenty of liquids to help prevent kidney stones. Check with your doctor about the amount of liquid you should drink each day. You should also increase your fiber intake.
You may need to lessen your intake of animal protein, sodium, refined sugars, or foods rich in oxalate and calcium, especially if you have kidney stones that keep coming back.
The dose of allopurinol will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of allopurinol. If your dose is different, do not change it unless your doctor tells you to do so.
The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.
- For oral dosage form (tablets):
- For gout:
- Adults—At first, 100 to 300 milligrams (mg) per day, taken once a day or in divided doses. Your doctor may adjust your dose as needed. However, the dose is usually not more than 800 mg per day.
- Children—Use and dose must be determined by your doctor.
- For high uric acid levels caused by cancer medicines:
- Adults and children 11 years of age and older—600 to 800 milligrams (mg) per day, taken in divided doses for 2 to 3 days.
- Children 6 to 10 years of age—300 mg per day, taken once a day for 2 to 3 days.
- Children younger than 6 years of age—150 mg per day, taken once a day for 2 to 3 days.
- For kidney stones:
- Adults—200 to 300 milligrams (mg) per day, taken once a day or in divided doses. Your doctor may adjust your dose as needed. However, the dose is usually not more than 800 mg per day.
- Children—Use and dose must be determined by your doctor.
- For gout:
If you miss a dose of allopurinol, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses.
Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. Keep from freezing.
Keep out of the reach of children.
Do not keep outdated medicine or medicine no longer needed.
Ask your healthcare professional how you should dispose of any medicine you do not use.
Precautions while using allopurinol
It is very important that your doctor check your or your child's progress at regular visits to make sure that allopurinol is working properly. Blood and urine tests may be needed to check for unwanted effects.
When you start using allopurinol, you may have more gout attacks. Keep using the medicine even if this happens. Your doctor may give you other medicines (eg, colchicine, pain medicines [NSAIDs]) to help prevent the gout attacks.
Serious skin reactions can occur with allopurinol. Call your doctor right away at the first appearance of a skin rash or allergic reaction (eg, trouble breathing or swallowing, swelling of your hands, face, or mouth). Check with your doctor if you also develop blistering, peeling, or loosening of the skin, red skin lesions, severe acne, or sores or ulcers on the skin.
Check with your doctor right away if you or your child have stomach pain or tenderness, pale stools, dark urine, loss of appetite, nausea, unusual tiredness or weakness, or yellow eyes or skin. These could be symptoms of a serious liver problem.
Allopurinol may cause some people to become drowsy or less alert than they are normally. Do not drive or do anything else that could be dangerous until you know how allopurinol affects you.
Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines and herbal or vitamin supplements.
Allopurinol side effects
Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.
Check with your doctor immediately if any of the following side effects occur:
- Ankle, knee, or great toe joint pain
- joint stiffness or swelling
- rash with flat lesions or small raised lesions on the skin
- ammonia-like breath odor
- bleeding gums
- blistering, peeling, or loosening of the skin
- blood in the urine or stools
- bloody nose
- bloody or black, tarry stools
- blue or pale skin
- changes in skin color
- chest pain or discomfort
- chest pain, possibly moving to the left arm, neck, or shoulder
- clay-colored stools
- cloudy urine
- coughing up blood
- cracks in the skin
- dark urine
- decreased awareness or responsiveness
- decreased urine output
- difficulty with breathing
- dry mouth
- feeling of warmth or heat
- flushing or redness of the skin, especially on the face and neck
- general feeling of discomfort or illness
- hives or welts, itching, skin rash
- incoherent speech
- increased urination
- joint or muscle pain
- large, flat, blue or purplish patches in the skin
- light-colored stools
- loss of appetite
- loss of consciousness
- loss of heat from the body
- lower back or side pain
- metallic taste
- muscle twitching
- muscle weakness
- noisy breathing
- pain, tenderness, or swelling of the foot or leg
- painful or difficult urination
- pinpoint red or purple spots on the skin
- rapid weight gain
- red, irritated eyes
- red, swollen skin
- redness, soreness, or itching skin
- right upper abdominal or stomach pain and fullness
- scaly skin
- severe sleepiness
- severe stomach pain
- slow or irregular heartbeat
- sore throat
- sores, ulcers, or white spots on the lips or in the mouth
- sores, welting, or blisters
- stomach pain
- swelling of the face, ankles, hands, or lower legs
- swollen or painful glands
- swollen, painful, or tender lymph glands in the neck, armpit, or groin
- tightness in the chest
- unpleasant breath odor
- unusual bleeding or bruising
- unusual drowsiness, dullness, tiredness, weakness, or feeling of sluggishness
- unusual weight gain or loss
- vomiting of blood or material that looks like coffee grounds
- yellow eyes or skin
Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:
- Bad, unusual, or unpleasant (after) taste
- blue-yellow color blindness
- blurred vision
- body aches or pain
- burning feeling in the chest or stomach
- burning, crawling, itching, numbness, prickling, "pins and needles", or tingling feelings
- burning, dry, or itching eyes
- change in taste
- change in vision
- continuing ringing or buzzing or other unexplained noise in the ears
- decreased interest in sexual intercourse
- decreased vision
- difficulty with moving
- discharge or excessive tearing
- feeling of constant movement of self or surroundings
- hair loss or thinning of the hair
- hearing loss
- impaired vision
- inability to have or keep an erection
- lack or loss of strength
- loss in sexual ability, desire, drive, or performance
- loss of appetite
- loss of memory
- multiple swollen and inflamed skin lesions
- muscle pain, cramps, or stiffness
- muscular pain, tenderness, wasting, or weakness
- problems with memory
- redness, pain, or swelling of the eye, eyelid, or inner lining of the eyelid
- runny nose
- sensation of spinning
- sensitivity to light
- sleepiness or unusual drowsiness
- stomach upset
- stuffy nose
- swelling of the breasts or breast soreness in both females and males
- swelling of the salivary glands
- swelling or inflammation of the mouth
- tender, swollen glands in the neck
- tenderness in the stomach area
- throbbing pain
- trouble getting pregnant
- trouble with sleeping
- trouble with swallowing
- unsteadiness or awkwardness
- voice changes
- weakness in the arms, hands, legs, or feet
- weight loss
Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.
Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.
More about allopurinol
- Side Effects
- During Pregnancy or Breastfeeding
- Dosage Information
- Patient Tips
- Drug Images
- Drug Interactions
- Compare Alternatives
- Support Group
- Pricing & Coupons
- En Español
- 80 Reviews
- Drug class: antigout agents
- Patient Information
- Allopurinol Intravenous (Advanced Reading)
- Allopurinol Tablets
- Allopurinol Injection
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