famotidine vs tizanidine
Side-by-side comparison of famotidine and tizanidine. Data from FDA drug databases (Orange Book, NDC Directory, recalls, shortages) covering 20,000+ approved drugs, plus CMS pricing; see our methodology.
moderate Known Drug Interaction
( 7.1 ) • Tizanidine (CYP1A2) Substrate: Potential for substantial increases in blood concentrations of tizanidine resulting in hypotension, bradycardia or excessive drowsiness; avoid concomitant use, if possible. 7.2 Tizanidine (CYP1A2 Substrate) Although not studied clinically, famotidine is considered a weak CYP1A2 inhibitor and may lead to substantial increases in blood concentrations of tizanidine, a CYP1A2 substrate. Refer to the full prescribing information for tizanidine.
Recommendation: Avoid taking these two drugs together if possible to prevent side effects like very low blood pressure or extreme drowsiness.
Pepcid
Zanaflex
Famotidine (Pepcid) reduces stomach acid. It is used to treat ulcers, heartburn, and acid reflux.
Tizanidine is a muscle relaxant. It is used to treat spasticity, which is when your muscles are tight or stiff.
This medicine treats active duodenal ulcers and active gastric ulcers. It also treats heartburn (nonerosive GERD) and erosive esophagitis (damage to the esophagus from acid reflux). Famotidine can also treat conditions where the stomach makes too much acid, like Zollinger-Ellison syndrome. It can also lower the risk of duodenal ulcers coming back.
Tizanidine is used to treat spasticity in adults. Spasticity is a condition where your muscles become stiff or tight. This medicine helps to relax your muscles and reduce the stiffness. It can help you move and feel more comfortable.
Famotidine is an H2 receptor antagonist. This means it blocks histamine, a substance that tells your stomach to make acid. By blocking histamine, famotidine reduces the amount of acid your stomach produces.
Tizanidine works by affecting certain chemicals in your brain. It is an alpha-2 adrenergic agonist. This action helps to reduce muscle spasms and tightness.
- • Headache
- • Dizziness
- • Constipation
- • Diarrhea
- • Dry mouth
- • Sleepiness
- • Weakness
- • Dizziness
- Feeling sick to your stomach 7,259
- Feeling tired 6,866
- Long-term kidney problems 6,644
- Loose, watery stools 6,448
- Difficulty breathing 5,203
- Tiredness 1,693
- Aches 1,615
- Feeling sick to your stomach 1,530
- Falling down 1,318
- Head pain 1,289
In elderly patients and those with kidney problems, famotidine can cause confusion, delirium, or hallucinations. If you are elderly or have kidney problems, your doctor may prescribe a lower dose. Famotidine can hide the symptoms of stomach cancer. If your symptoms don't improve, tell your doctor.
Tizanidine can cause low blood pressure, liver problems, and hallucinations. It can also make you very sleepy, especially if you drink alcohol or take other medicines that cause sleepiness. Your doctor should check your liver function before you start taking tizanidine and one month after you reach your highest dose. Do not stop taking tizanidine suddenly, as this can cause withdrawal symptoms.
It is not known if famotidine will harm an unborn baby. Talk to your doctor if you are pregnant or plan to become pregnant. Famotidine may pass into breast milk, but it's not expected to harm the baby. Talk to your doctor about breastfeeding while taking this medicine.
Tizanidine may harm your unborn baby. Talk to your doctor if you are pregnant or plan to become pregnant. It is not known if tizanidine passes into breast milk, so talk to your doctor if you are breastfeeding.
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How to Read This famotidine vs tizanidine Comparison
famotidine is classified in the H2 Receptor Antagonist drug class, while tizanidine sits within the Central Alpha-2 Agonist (Muscle Relaxant) class. Drugs from different classes work through distinct mechanisms, so a head-to-head comparison illustrates trade-offs rather than equivalence. Both drugs are split between OTC and prescription status, which affects access and supervision.
Adverse event totals above are pulled from the FDA's Adverse Event Reporting System (FAERS). For these top-ranked reactions alone, famotidine has 32,420 submissions while tizanidine has 7,445. 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 moderate interaction flagged in FDA labeling, attributed to famotidine can slow down the body's ability to clear tizanidine, which may lead to dangerously high levels of the drug in your blood.. Serious warnings, pregnancy guidance, and contraindications can differ even when indications overlap.
A table cannot substitute for clinical judgment. Effectiveness, tolerability, drug-drug interactions with your other medications, kidney and liver function, pregnancy status, insurance formulary, and price all feed into a decision that only a licensed prescriber can make responsibly. Data here is sourced from FDA Structured Product Labels (SPL) and FAERS, both of which update as manufacturers and clinicians submit new information. This page is for educational purposes only, is not medical advice, and should not be used to self-switch between famotidine and tizanidine - always consult your physician or pharmacist first.
Important: This comparison is for informational purposes only. Drug effects vary between individuals. Always consult your doctor or pharmacist for personalized medical advice.