allopurinol
Allopurinol (Zyloprim) is a xanthine oxidase inhibitor that lowers uric acid levels in the body. It's used to treat gout in adults. This prescription medication can also prevent recurrent calcium oxalate kidney stones in adults. In addition, allopurinol (Zyloprim) helps prevent tumor lysis syndrome in people with cancer who are taking certain chemotherapy (cancer medications). Allopurinol (Zyloprim) is a lower-cost generic tablet that's taken by mouth. Side effects are generally mild but can include diarrhea and nausea.
What is Allopurinol (Zyloprim)?
What is Allopurinol (Zyloprim) used for?
Gout in adults
Prevention of tumor lysis syndrome from certain chemotherapy medications in adults and children with cancer
Recurrent calcium oxalate kidney stones in adults
How Allopurinol (Zyloprim) works
Allopurinol (Zyloprim) is a xanthine oxidase inhibitor. It works by stopping an enzyme (protein) called xanthine oxidase from making uric acid.
By keeping uric acid levels low, allopurinol (Zyloprim) helps improve gout symptoms like joint pain and damage. Keeping uric acid levels low also prevents kidney stones as well as complications of tumor lysis syndrome due to certain chemotherapy.
Drug Facts
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What are the side effects of Allopurinol (Zyloprim)?
Common Side Effects
- Diarrhea
- Nausea
- High liver enzyme levels
- Rash
Other Side Effects
- More gout attacks
- Headache
- Muscle or joint pain
- Nerve pain (e.g., numbness or tingling in arms or legs)
- Change or loss in taste
Serious Side Effects
- Severe skin reaction: rash, hives, painful blisters, skin reddening, skin peeling, sore throat, fever, swollen lymph nodes
- Severe allergic reaction: facial swelling, anaphylaxis (e.g., closing of the throat), trouble breathing
- Liver problems: severe nausea, vomiting, right-sided stomach pain, low or no appetite, fatigue, yellowing of the skin or eyes
- Low blood cell counts: fever, trouble breathing, chills, weakness, unusual bruising or bleeding, blood in urine or stool
Source: DailyMed
More on Allopurinol (Zyloprim) side effects
The following side effects have also been reported
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:
More common
Ankle, knee, or great toe joint pain
joint stiffness or swelling
rash
rash with flat lesions or small raised lesions on the skin
Rare
Agitation
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
bruising
changes in skin color
chest pain or discomfort
chest pain, possibly moving to the left arm, neck, or shoulder
chills
clay-colored stools
cloudy urine
confusion
coughing up blood
cracks in the skin
dark urine
decreased awareness or responsiveness
decreased urine output
difficulty with breathing
dizziness
drowsiness
feeling of warmth or heat
flushing or redness of the skin, especially on the face and neck
general feeling of discomfort or illness
headache
hives or welts, itching, skin rash
hoarseness
hostility
incoherent speech
increased urination
irritability
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
seizures
severe sleepiness
severe stomach pain
slow or irregular heartbeat
sores, ulcers, or white spots on the lips or in the mouth
sores, welting, or blisters
stomach pain
sweating
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
thirst
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
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:
Rare
Bad, unusual, or unpleasant (after) taste
blindness
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
congestion
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
indigestion
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
sensation of spinning
sensitivity to light
sleepiness or unusual drowsiness
stomach upset
sweating
swelling of the breasts or breast soreness in both females and males
swelling of the salivary glands
swelling or inflammation of the mouth
tearing
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
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.
Pros and cons of Allopurinol (Zyloprim)
Pros
First-choice option for treating gout
Can take with or without food
Available as a lower-cost generic
Cons
Might raise the risk for gout attacks in the first few weeks (since your uric acid levels are rapidly changing during this time)
Can cause kidney stones, especially in people who don't drink a lot of fluids
Possible risk for low blood cell levels and liver damage
Pharmacist tips for Allopurinol (Zyloprim)
Be sure to follow up with your prescriber about your symptoms and your uric acid levels. Your prescriber might adjust your dose of allopurinol (Zyloprim) so that it works as best as it can for you.
You can take allopurinol (Zyloprim) with or without food. But it's recommended to take it after meals to prevent stomach upset.
Allopurinol (Zyloprim) can make you sleepy and dizzy. Make sure to avoid driving or doing anything that requires concentration until you know how this medication affects you.
It's best to avoid alcohol while you're taking allopurinol (Zyloprim). It can worsen side effects like drowsiness and dizziness. Alcohol can also raise your risk for gout flares.
Make sure to stay hydrated while you're taking allopurinol (Zyloprim) to prevent kidney stones. It's recommended to drink at least 2 liters of liquids per day.
Discuss with your prescriber about which foods and beverages you should try to avoid while you're taking allopurinol (Zyloprim). Certain foods and drinks can worsen gout or raise your risk for kidney stones.
Tell your healthcare team and pharmacist about all the medications you're taking. Allopurinol (Zyloprim) can interact with some medications, and these interactions can harm you. Your care team and pharmacist can check for any drug interactions and make sure your medications are safe to take together.
Let your prescriber know right away if you're pregnant or thinking of becoming pregnant. It's not completely known how safe allopurinol (Zyloprim) is during pregnancy because study findings aren't consistent. Your prescriber can review the risks and benefits of taking the medication while pregnant with you.
Ask your prescriber whether allopurinol (Zyloprim) is safe to take if you're breastfeeding. This medication can get into breast milk, but it's not clear how it'll affect your baby. To be safe, it's recommended to avoid breastfeeding during treatment and for at least 1 week after your last allopurinol (Zyloprim) dose. Speak with your prescriber about your options if you need to continue treatment while you're breastfeeding.
Frequently asked questions about Allopurinol (Zyloprim)
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What are the risks and warnings for Allopurinol (Zyloprim)?
Allopurinol (Zyloprim) can cause some serious health issues. This risk may be even higher for certain groups. If this worries you, talk to your doctor or pharmacist about other options.
Severe skin reaction
Risk factors: Having a certain gene called HLA-B 58:01, which raises your risk for reactions | African or Asian descent | Kidney problems and take thiazide diuretics | Taking bendamustine, ampicillin, or amoxicillin
Although rare, allopurinol (Zyloprim) can cause severe and life-threatening skin reactions. These skin reactions can include Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), and drug reaction with eosinophilia and systemic symptoms (DRESS). The risk appears to be highest in the first few months of treatment.
Your prescriber might run some tests to check whether you have a gene called HLA-B 58:01 if you're of African or Asian descent. People of African or Asian descent are more likely to carry this gene, and the gene raises the risk for these reactions. Allopurinol (Zyloprim) isn't recommended if you have the HLA-B 58:01 gene, unless the benefits outweigh the risks.
Stop allopurinol (Zyloprim) and get medical attention right away if you notice a rash, other unusual changes in your skin (e.g., painful blisters, skin reddening, skin peeling), fever, or swollen lymph nodes.
More gout attacks
It's possible to have more gout flares within the first several months of starting allopurinol (Zyloprim). Gout flares can happen because the medication quickly lowers your uric acid levels. And these changes in uric acid levels can irritate your joints and lead to inflammation.
Your HCP might prescribe another medication, such as colchicine (Colcrys), for you to take with allopurinol (Zyloprim) to help prevent gout attacks. Let your prescriber know if you experience any gout attacks after you start allopurinol (Zyloprim).
Kidney stones and kidney injury
Risk factors: History of kidney problems or kidney stones | Dehydration
People who take allopurinol (Zyloprim) can develop kidney stones. Sometimes, these kidney stones can lead to kidney injury. The risk might be higher for people who already have kidney problems or who've had kidney stones before.
Stay hydrated and drink at least 2 liters of fluid per day. This helps your body get rid of more uric acid and prevents kidney stones from forming. Also try avoiding foods that can raise your risk for kidney stones. Get medical help if you have severe sharp pain towards your side and back, nausea, vomiting, or pain or burning when urinating. These might be signs of a kidney stone.
Liver damage
Allopurinol (Zyloprim) might cause liver damage, but it tends to be reversible when the medication is stopped. This effect is usually mild but can be dangerous in rare cases. Your prescriber will periodically check the liver enzyme levels in your blood to make sure your liver is working properly during treatment if you already have liver problems. Call your prescriber if you start having low or no appetite, weight loss, itching, or yellowing of the skin or eyes; you'll need to get checked for liver damage.
Low blood cell counts
Although rare, some people who took allopurinol (Zyloprim) had low blood cell counts. This means that they had a drop in the number of red blood cells, white blood cells, or platelets in their blood. Low blood cell counts can happen as early as a month and up to several years after starting this medication. Having low blood cell counts can put you at risk for anemia, infections, and easy bleeding or bruising.
Your prescriber might measure your complete blood count (CBC) during treatment with allopurinol (Zyloprim) to make sure your blood cell counts don't get too low. Contact your prescriber if you have any symptoms of low blood cell counts, such as fever, shortness of breath, chills, weakness, and unusual bruising or bleeding.
Sleepiness and dizziness
Risk factors: Taking high doses of allopurinol (Zyloprim) | Taking other medications that can cause sleepiness
Some people can feel very dizzy or sleepy after they take allopurinol (Zyloprim). Dizziness and sleepiness can affect your ability to think, react, and focus. You're at higher risk for these side effects if you're also taking other medications that can cause drowsiness, such as benzodiazepines, muscle relaxants, and sleep medications.
Make sure you know how allopurinol (Zyloprim) affects you when you first start treatment or when your dose changes before driving a car or doing activities that require your concentration. Talk to your healthcare team if you feel too dizzy or sleepy from taking this medication.
Allopurinol (Zyloprim) dosage forms
Typical dosing for Allopurinol (Zyloprim)
In general, the dose can be taken once a day. It can also be split into smaller doses throughout the day, especially if the dose is more than 300 mg and if specifically instructed for your condition.
Your dose will be adjusted depending on your uric acid levels and the severity of your condition. It can also differ if you have kidney problems.
Gout: The typical starting dose is 100 mg by mouth per day. Then, the dose is typically raised to a range of 200 mg to 600 mg per day.
High uric acid levels from chemotherapy:
Adults: The typical dose is 300 mg to 800 mg by mouth per day. You'll start allopurinol (Zyloprim) a day or two before getting chemotherapy and continue allopurinol (Zyloprim) until 2 or 3 days after your chemotherapy session.
Children: The dose is calculated based on your child's body size. This medication is taken by mouth every 8 to 12 hours. Your child will start allopurinol (Zyloprim) a day or two before getting chemotherapy and will continue allopurinol (Zyloprim) until 2 or 3 days after their chemotherapy session.
Recurrent calcium oxalate kidney stones: The typical dose is 200 mg to 300 mg by mouth per day.
The maximum daily dose is 800 mg.
More on Allopurinol (Zyloprim) dosage forms
Interactions between Allopurinol (Zyloprim) and other drugs
More on Allopurinol (Zyloprim) interactions
Using this medicine 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 this medicine 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.
- Acenocoumarol
- Azathioprine
- Capecitabine
- Captopril
- Enalapril
- Enalaprilat
- Fluorouracil
- Mercaptopurine
- Pegloticase
- Phenprocoumon
- Tegafur
- Warfarin
Using this medicine 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
- Cyclosporine
- Vidarabine
How much does Allopurinol (Zyloprim) cost?
What are alternatives to Allopurinol (Zyloprim)?
Gout in adults
Prevention of tumor lysis syndrome from certain chemotherapy medications in adults and children with cancer
Recurrent calcium oxalate kidney stones in adults
Gout in people who can't take or haven't responded to allopurinol (Zyloprim)
Gout prevention
Gout treatment - tablets only
Familial Mediterranean fever (FMF) - tablets only
What is the latest news about Allopurinol (Zyloprim)?
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References
Best studies we foundAdeyinka, A., et al. (2022). Tumor lysis syndrome. StatPearls.
Casper Pharma LLC. (2023). Zyloprim - allopurinol tablet [package insert]. DailyMed.
Connor, M. (2009). Allopurinol for pain relief: More than just crystal clearance? British Journal of Pharmacology.
Drugs and Lactation Database (LactMed®). (2022). Allopurinol. National Institute of Child Health and Human Development.
Ferdiana, A., et al. (2022). Allopurinol-Induced Stevens–Johnson Syndrome in Javanese Men With Positive HLA‐B*58:01. Frontiers in Genetics.
Gupta, A., et al. (2018). Tumor lysis syndrome. Journal of the American Medical Association Oncology.
InformedHealth.org. (2023). Kidney stones: Learn more – Preventing kidney stones. Institute for Quality and Efficiency in Health Care.
MedlinePlus. (2023). Uric acid - blood.
National Kidney Foundation. (2019). Calcium oxalate stones.
Simsek, M., et al. (2018). The teratogenicity of allopurinol: A comprehensive review of animal and human studies. Reproductive Toxicology.
Stamp, L. K., et al. (2017). How to prevent allopurinol hypersensitivity reactions? Rheumatology.
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