Mesnex (Mesna) - Oral

What Is Mesnex?

Mesnex (mesna), also known as sodium-2-mercaptoethanesulfonate, is an antioxidant (a human-made or natural substance that may prevent or delay cell damage) that is used to lower the risk of hemorrhagic cystitis in people who take a medication called ifosfamide (a chemotherapy drug, or a drug used to treat cancer).

The medication, prescribed for people older than premature neonates or low-birth-weight infants, is administered via intravenous (IV) injection and oral tablets.

Mesnex is classified as a cytoprotective agent as it serves to protect cells. It works by chemically reacting with ifosfamide metabolites (a substance made from the breakdown of ifosfamide in the body), detoxifying them, and stopping them from harming the bladder.

Mesnex is available as a liquid solution to be administered via IV into a vein and as an oral tablet to be consumed orally. Comparatively, under the generic title, mesna is solely available as an IV solution.

This article will focus on the oral, film-coated tablet version of Mesnex.

Drug Facts

Generic Name: Mesna

Brand Name(s): Mesnex

Drug Availability: Prescription

Therapeutic Classification: Hemorrhagic cystitis inhibitor

Available Generically: Not in oral tablet form, IV only

Controlled Substance: N/A

Administration Route: Oral/injection

Active Ingredient: Sodium-2-mercaptoethanesulfonate

Dosage Form(s): Tablet (initial dose: IV solution)

What Is Mesnex Used For?

The Food and Drug Administration (FDA) approved Mesnex as a prophylactic drug (a drug that prevents infection) to decrease the incidence of hemorrhagic cystitis caused by the chemotherapy drug ifosfamide. This condition is also known as ifosfamide-induced hemorrhagic cystitis.

Hemorrhagic cystitis is a condition where the bladder's lining becomes inflamed and bleeds. Besides blood in the urine, other symptoms include pain and burning upon urination, feeling an urgency to urinate frequently, and being unable to control urine flow. Chemotherapy drugs, such as ifosfamide, can cause hemorrhagic cystitis, and Mesnex is used to lower the risk of hemorrhagic cystitis.

Mesnex does not prevent hemorrhagic cystitis in all people. However, it does not prevent other side effects associated with ifosfamide. 

Mesnex is not used to lower the risk of blood in the urine caused by other medical conditions, such as low platelet levels.

How to Take Mesnex

If you are prescribed Mesnex, read the prescription label and information leaflet that comes with your prescription. Consult your healthcare provider if you have any questions. Use Mesnex exactly as directed by your healthcare provider, at the exact times and exact dose.

Mesnex is taken on the same days that you receive the chemotherapy drug ifosfamide. Mesnex can be given by IV infusion or tablets that are taken by mouth.

If you take all doses of Mesnex by IV infusion, you will receive Mesnex when you receive ifosfamide and again four hours and eight hours after you receive ifosfamide.

For those who take the oral tablets, you will receive your first dose of Mesnex by IV infusion when you receive ifosfamide. Then, you will take Mesnex oral tablets by mouth two and six hours after you receive ifosfamide.

Wash your hands after handling Mesnex. While taking Mesnex, drink 4 to 8 cups of liquid every day. This is equal to 1 or 2 liters. Notify your healthcare provider if you vomit within two hours of taking Mesnex, miss a dose of Mesnex, or if your urine is pink or red. Keep all appointments with your healthcare provider and for lab work/urine tests.

Mesnex can interfere with certain lab tests. Tell the phlebotomist (the person that draws your blood) at the lab that you take Mesnex.

Ask your healthcare provider if you have any questions or concerns about Mesnex.


Regarding Mesnex tablets, store them at room temperature, away from direct light, heat, and moisture. Do not store it in the bathroom. Keep this medication in its original labeled container and out of reach and out of sight of children and pets. Keep the bottle tightly closed when not in use.

For the initial IV use, expect a healthcare provider to administer the dose when you get your chemotherapy drug.

Off-Label Uses

Sometimes, Mesnex is used off-label for indications that are not FDA-approved. Healthcare providers may prescribe oral Mesnex in people to prevent cyclophosphamide-induced hemorrhagic cystitis or hemorrhagic cystitis due to the drug cyclophosphamide.

How Long Does Mesnex Take to Work?

Taken by mouth, Mesnex starts to reach its peak effect at about 90 minutes.

What Are the Side Effects of Mesnex?

This is not a complete list of side effects, and others may occur. A healthcare provider can advise you on side effects. If you experience other effects, contact your pharmacist or a healthcare provider. You may report side effects to the FDA at or 1-800-FDA-1088.

Like other medications, Mesnex can cause side effects. Tell your healthcare provider about any side effects you experience while taking this medication.

Common Side Effects

The most common side effects of Mesnex, alone, include:

The prescribing information notes that the most common side effects that occur when Mesnex is given with ifosfamide include:

  • Stomach problems: Nausea, vomiting, constipation or diarrhea, stomach pain
  • Low white blood cells (which can interfere with the body's ability to fight infection)
  • Low red blood cells
  • Low platelet levels (which can cause easy bruising and bleeding, such as nosebleeds and bleeding gums)
  • Tiredness/drowsiness and weakness
  • Fever
  • Appetite loss
  • Headache
  • Hair loss

Severe Side Effects

Call your healthcare provider right away if you have serious side effects. Call 911 if your symptoms feel life-threatening or if you think you’re having a medical emergency. Serious side effects and their symptoms can include the following:

  • Hypersensitivity reaction or anaphylaxis: Symptoms can include rash, hives, swelling around the lips, tongue, and face, and difficulty breathing, and require emergency medical attention. 
  • Severe skin reaction: Be alert to fever, sore throat, burning sensation, swelling, puffy eyes, mouth sores, flushing, hives, redness, itching, red or purple rash, blistering or peeling skin.

Long-Term Side Effects

Some long-term or delayed side effects that may occur with Mesnex include:

  • Appetite loss
  • Weakness
  • Hair loss
  • Joint and back pain
  • Skin reactions (can be life-threatening and can cause death if not treated)
  • Constipation
  • Low levels of platelets
  • Low white blood cells
  • Low red blood cells
  • Liver problems

Report Side Effects

Mesnex may cause other side effects. Call your healthcare provider if you have any unusual problems while taking this medication. If you experience a serious side effect, you or your healthcare provider may send a report to the FDA's MedWatch Adverse Event Reporting Program or by phone (800-332-1088).

Dosage: How Much Mesnex Should I Take?

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The dose of this medicine 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 this medicine. 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 prevention of hemorrhagic cystitis:
      • Adults—Dose must be determined by your doctor. Your dose will usually be taken 2 hours and 6 hours after each dose of ifosfamide.
      • Children—Use and dose must be determined by your doctor.


Users should be aware of the following before beginning Mesnex:

Older adults: You may need to use caution when taking Mesna if you are 65 or older, especially if you have other medical conditions.

People with kidney or liver problems: People with kidney or liver problems should consult their healthcare provider, as there are no clinical trials that have studied Mesnex in people with kidney or liver conditions.

Pregnant people: Mesnex is used in combination with the drug ifosfamide and other drugs that could harm or cause death to an unborn baby. People who are pregnant should consult their healthcare provider for medical advice.

Contraceptive use: Because Mesnex is used with ifosfamide and other drugs that could harm or cause death to an unborn baby, healthcare providers will give a pregnancy test to verify pregnancy status before prescribing Mesnex.

People of childbearing age should use effective contraception while taking Mesnex with ifosfamide and for six months after the last dose. People with partners of childbearing age should use effective contraception while taking Mesnex with ifosfamide and for three months after the last dose. You can discuss methods of effective contraception with your healthcare provider. Report pregnancy right away if you or your partner are taking ifosfamide.

Nursing people: Although there is no data on Mesnex use alone in nursing people, it is taken with ifosfamide, which is present in breast milk and could cause harm to the baby. Because of this risk, people should not breastfeed during treatment with Mesnex or ifosfamide and for at least one week after the last dose.

Missed Dose

If you miss a dose of Mesnex, contact your healthcare provider for instructions.

Overdosage: What Happens If I Take Too Much Mesnex?

An overdose may cause nausea, vomiting, diarrhea, and fever, as well as hypotension (low blood pressure), shortness of breath/worsening of asthma, rash, and flushing.

What Happens If I Overdose on Mesnex?

If you think you or someone else may have overdosed on Mesnex, call a healthcare provider or the Poison Control Center (800-222-1222). If someone collapses or isn't breathing after taking Mesnex, call 911 immediately.


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It is very important that your doctor check your progress at regular visits to make sure this medicine is working properly. Blood and urine tests will be needed to check for unwanted effects.

This medicine is used together with ifosfamide. Ifosfamide can harm your unborn baby while you are pregnant. It may also cause birth defects if the father is using it when his sexual partner becomes pregnant. Use an effective form of birth control during treatment with this medicine in combination with ifosfamide and for 6 months after the last dose. Male patients with female partners should use an effective form of birth control during treatment and for 3 months after the last dose. If you think you have become pregnant while using this medicine, tell your doctor right away.

This medicine may cause serious allergic reactions, including anaphylaxis, which can be life-threatening and require immediate medical attention. The most serious signs of this reaction are very fast or irregular breathing, gasping for breath, or fainting. Other signs may include: changes in facial skin color, very fast but irregular heartbeat or pulse, hive-like swellings on the skin, and puffiness or swellings of the eyelids or around the eyes. If these side effects occur, get emergency help at once.

Serious skin reactions can occur with this medicine. Check with your doctor right away if you have blistering, peeling, or loosening of the skin, red skin lesions, severe acne or skin rash, sores or ulcers on the skin, or fever or chills while you are using this medicine.

Make sure any doctor or dentist who treats you knows that you are using this medicine. It may affect the results of certain medical tests.

What Are Reasons I Shouldn't Take Mesnex?

Mesnex is not appropriate for everyone. Before taking Mesnex, tell your healthcare provider about all of your medical conditions, your medical history, and your family history.

You should not take this medication if you are allergic to mesna or any of the inactive ingredients in Mesnex. 

Other people who should not take Mesnex include:

  • People who are allergic to thiol compounds (such as N-acetylcysteine)
  • Newborns and infants (should not take the IV form of Mesnex [mesna])
  • Nursing people

Although this article focuses on oral Mesnex, a dose of IV Mesnex is given before the oral Mesnex is taken. Therefore, it is important to note that Mesnex injection (but not tablets) contains an ingredient called benzyl alcohol that can cause serious side effects or death in premature babies or low-birthweight babies. Mesna tablets do not contain this ingredient. Premature babies or low birth weight infants should not be given Mesnex injections.

Mesnex may be prescribed with caution in some people only if the healthcare provider determines it is safe. This includes:

  • Children (the IV form should be used with caution)
  • People with an autoimmune condition

What Other Medications May Interact With Mesnex?

There are no drug interactions associated with Mesnex. Still, tell your healthcare provider about all of the medicines you take, including prescription and over-the-counter (OTC) medicines, and vitamins or supplements.

What Medications Are Similar?

Due to a lack of modern studies, potential users should assume Mesnex to be the standard for treating hemorrhagic cystitis in people taking the chemotherapy drug ifosfamide.

Therefore, people who cannot tolerate it should consult their healthcare provider for other potential treatment options.

Frequently Asked Questions

  • What is Mesnex used for?

    Mesnex is known as a cytoprotectant drug. It is used to prevent hemorrhagic cystitis, a condition where the lining of the bladder becomes inflamed and bleeds, caused by the chemotherapy drug ifosfamide.

  • How does Mesnex work?

    Mesnex works by chemically reacting with metabolites of ifosfamide, detoxifying them, and preventing them from harming the bladder.

  • What drugs interact with Mesnex?

    Mesnex does not have any drug interactions. However, it would help if you still tell your healthcare provider about all your medications, including prescription and over-the-counter (OTC) drugs, vitamins, and supplements.

How Can I Stay Healthy While Taking Mesnex?

Here are some tips on how to handle side effects that may arise from taking Mesnex along with your chemotherapy regimen:


  • Spread out your activities for the day, allowing for rest in between activities.


  • To help prevent infection, wash your hands regularly.
  • Avoid coming in close contact with people who are sick.
  • Monitor your temperature as directed by your healthcare provider and when you feel like you may have a fever.


  • To help decrease the risk of bleeding, brush your teeth with a soft-bristled toothbrush. Ask your healthcare provider if you should floss.
  • Use extra caution around knives and other tools.
  • Shave with an electric razor.

Hydration/stomach upset:

  • Drink 4 to 8 cups of fluids every day, or as directed by your healthcare provider.
  • If you have vomiting or diarrhea, increase fluid intake to avoid dehydration. Ask your healthcare provider how much extra fluid you should drink.
  • Avoid foods that bother your stomach if you have diarrhea, and stick to lower-fiber foods.
  • Ask your healthcare provider about medication if you have diarrhea or constipation. Check with your healthcare provider before using medication.
  • If you have nausea and vomiting, eat small meals more often, rather than three large meals. It may help to eat and drink room temperature foods and beverages.
  • If you have a decreased appetite, choose foods and high-quality drinks that are high-calorie and high-protein, such as meats, eggs, nuts, cheese, ice cream, and nutritional supplement beverages.

Hair loss:

  • Wash hair with a mild shampoo, but do not wash your hair every day.
  • Gently pat your hair dry.
  • Avoid chemicals/hair coloring and heat, such as hairdryers and flat irons.
  • If you are interested in a wig, ask your healthcare provider, or contact the American Cancer Society at 800-ACS-2345. Their “Look Good, Feel Better” program is a free program where women on chemotherapy can learn about wigs as well as other cosmetic care.

Medical Disclaimer

Verywell Health's drug information is meant for educational purposes only and is not intended as a replacement for medical advice, diagnosis, or treatment from a healthcare provider. Consult your healthcare provider before taking any new medication(s). IBM Watson Micromedex provides some of the drug content, as indicated on the page.

8 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. DailyMed. Label: Mesnex - mesna tablet, film coated.

  2. MedlinePlus. Mesna.

  3. MedlinePlus. Mesna injection.

  4. National Cancer Institute. Hemorrhagic cystitis.

  5. Jaiswal SR, Singhal P, Thatai A, et al. Impact of extended infusional mesna prophylaxis on the incidence of BK viruria and hemorrhagic cystitis following post-transplantation cyclophosphamide and CTLA4Ig-based haploidentical transplantationAnn Hematol. 2020;99(4):839-845. doi:10.1007/s00277-020-03930-w

  6. Epocrates. Mesnex

  7. Prescribers’ Digital Reference. Mesna - drug summary.

  8. UPMC Hillman Cancer Center. Mesna.

By Karen Berger, PharmD
Karen Berger, PharmD, is a community pharmacist and medical writer/reviewer.