allopurinol vs famciclovir
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Side-by-side comparison of allopurinol and famciclovir. Data from FDA drug databases (Orange Book, NDC Directory, recalls, shortages) covering 20,000+ approved drugs, plus CMS pricing; see our methodology.
minor Known Drug Interaction
7.2 Potential for Other Drugs to Affect Penciclovir No clinically significant alterations in penciclovir pharmacokinetics were observed following single-dose administration of 500 mg famciclovir after pretreatment with multiple doses of allopurinol, cimetidine, theophylline, zidovudine, promethazine, when given shortly after an antacid (magnesium and aluminum hydroxide), or concomitantly with emtricitabine.
Zyloprim
Famvir
Allopurinol is a medicine that lowers uric acid levels in your body. It helps prevent gout attacks and other problems caused by high uric acid.
Famciclovir is an antiviral medicine. It helps to treat infections caused by certain viruses.
This medicine is used to manage gout in adults. Gout causes painful attacks, joint damage, and kidney problems. Allopurinol is also used in adults and children with leukemia, lymphoma, and solid tumors who are getting cancer treatment. It helps manage high uric acid caused by the cancer treatment. It can also help adults who get calcium oxalate kidney stones often.
This medicine treats herpes infections. It can treat cold sores, genital herpes, and shingles. It can also prevent genital herpes outbreaks. This medicine may not work for everyone, including first-time genital herpes, eye shingles, or certain immunocompromised patients.
Allopurinol works by blocking an enzyme called xanthine oxidase. This enzyme helps your body make uric acid. By blocking it, allopurinol reduces the amount of uric acid in your blood and urine.
Famciclovir stops the virus from multiplying. It does this by blocking a key enzyme the virus needs to make copies of itself. This helps your body fight off the infection.
- • Diarrhea
- • Nausea
- • Increased liver enzyme levels
- • Gout attacks
- • Skin rash
- • Headache
- • Nausea
- Diarrhoea 8,423
- Fatigue 7,965
- Dyspnoea 7,658
- Nausea 7,063
- Death 6,665
- Fatigue 185
- Diarrhoea 179
- Nausea 145
- Headache 135
- Pain 118
Allopurinol can cause serious skin reactions that can be deadly. Stop taking this medicine and get medical help right away if you get a skin rash or any other signs of an allergic reaction.
If you have kidney problems, make sure your doctor knows. Taking too much famciclovir when you have kidney problems can damage your kidneys.
Allopurinol may harm your unborn baby. Talk to your doctor if you are pregnant or plan to become pregnant. It is not recommended to breastfeed while taking this medicine because it can pass into breast milk.
Tell your doctor if you are pregnant or plan to become pregnant. Untreated herpes during pregnancy can harm the baby. It is not known if famciclovir passes into breast milk.
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How to Read This allopurinol vs famciclovir Comparison
allopurinol is classified in the Xanthine Oxidase Inhibitor drug class, while famciclovir sits within the Antiviral (Nucleoside Analog) class. Drugs from different classes work through distinct mechanisms, so a head-to-head comparison illustrates trade-offs rather than equivalence. Both drugs are prescription-only, so a licensed provider must authorize use.
Adverse event totals above are pulled from the FDA's Adverse Event Reporting System (FAERS). For these top-ranked reactions alone, allopurinol has 37,774 submissions while famciclovir has 762. Those figures reflect cumulative reporting volume, not per-patient risk, so older, widely dispensed drugs typically look worse on count alone. These two drugs have a known minor interaction flagged in FDA labeling, attributed to these two drugs do not have a meaningful effect on how the body breaks down or uses either medicine.. Serious warnings, pregnancy guidance, and contraindications can differ even when indications overlap.
A table cannot represent individual circumstances. Data here is sourced from FDA Structured Product Labels (SPL) and FAERS, both of which update as manufacturers and clinicians submit new information. This registry does not provide medical, treatment, substitution, or medication-change directions for allopurinol or famciclovir.
Registry boundary: This comparison displays source-record fields and does not provide individualized medical direction.