Uses

What is methazolamide used for?

Methazolamide is commonly used to treat certain forms of glaucoma. Glaucoma is an eye condition where a buildup of pressure inside the eye damages the optic nerve and can cause vision loss. 

Methazolamide may also be used for other conditions as determined by your healthcare provider.

How does methazolamide work (mechanism of action)?

Methazolamide blocks an enzyme called carbonic anhydrase in the body. This helps lower pressure inside the eye. 

How is methazolamide supplied (dosage forms)?

Methazolamide is available in the following dosage forms that are taken by mouth.

  • 25 mg oral tablets
  • 50 mg oral tablets

How should I store methazolamide?

Methazolamide should be stored at room temperature, between 68 F to 77 F (20 C to 25 C). It can be exposed to temperatures between 59 F to 86 F (15 C to 30 C) for shorter periods of time, such as when transporting it. Store in a cool, dry place in a tightly closed container.

Side Effects

What are the most common side effects of methazolamide?

The most common side effects of methazolamide are listed below. Tell your healthcare provider if you have any of these side effects that bother you.

  • Numbness, tingling, or burning sensation in your arms, feet, or face 
  • Trouble hearing or hearing a ringing or buzzing sound in your ears
  • Tiredness or drowsiness
  • General feeling of being unwell, tired, or not having your usual energy
  • Loss of appetite
  • Change in how things taste
  • Nausea, vomiting, or diarrhea
  • Needing to pee much more often than usual
  • Confusion 
  • Trouble seeing faraway objects 

There may be other side effects of methazolamide that are not listed here. Contact your healthcare provider if you think you are having a side effect of a medicine. In the U.S., you can report side effects to the FDA at www.fda.gov/medwatch or by calling 800-FDA-1088. In Canada, you can report side effects to Health Canada at www.health.gc.ca/medeffect or by calling 866-234-2345.

What are the serious side effects of methazolamide?

While less common, the most serious side effects of methazolamide are described below, along with what to do if they happen.

Severe Allergic Reactions. Methazolamide may cause allergic reactions, which can be serious. Stop taking methazolamide and get help right away if you have any of the following symptoms of a serious allergic reaction.

  • Breathing problems or wheezing
  • Racing heart
  • Fever or general ill feeling
  • Swollen lymph nodes
  • Swelling of the face, lips, mouth, tongue, or throat
  • Trouble swallowing or throat tightness
  • Itching, skin rash, or pale red bumps on the skin called hives
  • Nausea or vomiting
  • Dizziness, feeling lightheaded, or fainting
  • Stomach cramps
  • Joint pain

Severe Skin Reactions. Methazolamide can cause severe skin reactions, called Stevens-Johnson Syndrome (SJS) and Toxic Epidermal Necrolysis (TEN), that can lead to death if not treated. If you develop a rash, stop methazolamide and call your healthcare provider right away. Get emergency help right away if you have any of the following symptoms of SJS or TEN.

  • Painful red or purple skin that looks burned and peels off
  • Flat red rash or blisters on your skin, mouth, nose, and genitals
  • Red, painful, watery eyes

Liver Damage. Liver damage, also called hepatotoxicity, can happen when taking methazolamide. Call your healthcare provider right away if you have any of the following symptoms of liver damage.

  • Nausea or vomiting
  • Stomach or belly pain
  • Fever
  • Weakness or unusual tiredness
  • Itching
  • Loss of appetite
  • Light-colored poop
  • Dark-colored urine (pee)
  • Your skin or the whites of your eyes turning yellowish in color (also called jaundice)

Blood Disorders. Methazolamide can cause blood disorders, such as agranulocytosisaplastic anemia, hemolytic anemia, and low white blood cell levels (leukopenia). Stop taking methazolamide and get help right away if you have any of the following symptoms of blood disorders.

  • Fever
  • Shortness of breath
  • Pale or yellowish skin
  • Easy bruising or bleeding
  • Frequent infection
  • Unusual weakness or tiredness
  • Dizziness, lightheadedness, or feeling like you are about to pass out
  • Headache
  • Fast or abnormal heartbeat

Kidney Stones. Methazolamide may cause kidney stones. Drinking plenty of water can help prevent kidney stones. Tell your healthcare provider right away if you develop severe pain in your side or back or have blood in your urine (pee). Your pee may look pink, red, or brown.

Metabolic Acidosis. Methazolamide can cause or worsen a condition called metabolic acidosis. Metabolic acidosis happens when there is too much acid in the blood. If this condition is not treated, it can cause kidney stones, slowed growth in children, your bones can become soft or brittle (osteoporosisosteomalacia (rickets)osteopenia), or cause harm to your unborn baby if you are pregnant. Tell your healthcare provider right away if you have any of the following symptoms of metabolic acidosis.

  • Fast breathing or heartbeat
  • Headache
  • Feeling confused, weak, or tired
  • Not feeling hungry
  • Nausea or vomiting

Electrolyte Changes. Methazolamide may cause changes to the levels of certain minerals in your body, called electrolytes. For example, it may cause low potassium levels (hypokalemia) or low sodium levels (hyponatremia). These changes can be serious. Keep appointments for blood work so that your healthcare provider can check your electrolyte levels, especially if you take certain other medicines. Call your healthcare provider if you have any of the following symptoms of electrolyte changes.

  • Weakness
  • Unusual tiredness
  • Muscle cramps or twitching
  • Constipation
  • Nausea, vomiting, or loss of appetite
  • Dizziness
  • Restlessness or irritability
  • Difficulty breathing
  • Confusion or decreased alertness

Warnings & Precautions

Who should not use methazolamide?

Allergies to Ingredients. People who are allergic to any of the following should not take methazolamide.

  • Methazolamide
  • Any of the ingredients in the specific product dispensed

Your pharmacist can tell you all of the ingredients in the specific methazolamide products they stock.

Kidney Problems. Methazolamide should not be taken if your kidneys are not working as well as they should be. If there is a concern about the health of your kidneys, your healthcare provider may do tests to determine if they are working well enough to take this medicine.

Liver Problems. Methazolamide should not be taken if your liver is not working as well as it should be. If there is a concern about the health of your liver, your healthcare provider may do tests to determine if it is working well enough to take this medicine.

Adrenal Gland Failure. Do not take methazolamide if you have adrenal gland failure, which is when your body’s adrenal glands are not able to make enough cortisol (a stress hormone). 

Hyperchloremic Acidosis. Do not take methazolamide if you have hyperchloremic acidosis. This is a condition caused by low levels of bicarbonate and high levels of chloride in the blood. This causes the blood to become too acidic. Your healthcare provider may do blood work to see if it is safe for you to take this medicine.  

Angle-closure Glaucoma. Do not take methazolamide for a long period of time if you have a certain type of glaucoma called angle-closure glaucoma. Angle-closure glaucoma is an eye condition where fluid buildup rapidly increases pressure inside the eye. This can cause sudden vision problems and pain. Ask your healthcare provider if you are not sure what type of glaucoma you have and whether it is safe for you to take methazolamide. 

Low Sodium Level (Hyponatremia). Do not take methazolamide if you have low sodium levels. Your healthcare provider may use lab tests to check your sodium levels to determine if the levels are safe to take this medicine.  

Low Potassium Level (Hypokalemia). Do not take methazolamide if you have low potassium levels. Your healthcare provider may use lab tests to check your potassium levels to determine if the levels are safe to take this medicine.  

What should I know about methazolamide before using it?

Do not take methazolamide unless it has been prescribed to you by a healthcare provider. Take it as prescribed.

Do not share methazolamide with other people, even if they have the same condition as you. It may harm them.

Keep methazolamide out of the reach of children.

Methazolamide can affect your alertness or coordination. Do not drive or do other activities that require alertness or coordination until you know how methazolamide affects you.

Methazolamide can make your skin more sensitive to light from the sun, sunlamps, and tanning beds. This is called photosensitivity. Exposure to this light can cause severe sunburns, blisters, and swelling. If you need to be in sunlight, wear sunscreen, a hat, and clothing that covers your skin.

What should I tell my healthcare provider before using methazolamide?

Tell your healthcare provider about all of your health conditions and any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. This will help them determine if methazolamide is right for you.

In particular, make sure that you discuss any of the following.

Sulfa Allergy. Some people who have a sulfa allergy may also be allergic to methazolamide. A sulfa allergy is a rash or more serious reaction to sulfa, or sulfonamide, medicines. Sulfa medicines include sulfamethoxazole, sulfadiazine silver, or sulfasalazine. Tell your healthcare provider if you have any allergies to medicines. Your healthcare provider can help you decide if it is safe for you to take methazolamide.

Current and Past Health Conditions. Tell your healthcare provider if you have any of the following.

  • Liver problems 
  • Lung problems
  • Kidney problems 
  • Low sodium level (hyponatremia) 
  • Low potassium level (hypokalemia) 

Other Medicines and Supplements. Methazolamide may interact with other medicines and supplements. Before taking methazolamide, tell your healthcare provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. See the Interactions section for more details.

Pregnancy. It is not known if or how methazolamide could affect pregnancy or harm an unborn baby. Tell your healthcare provider if you are or plan to become pregnant. 

Breastfeeding. It is not known if methazolamide passes into breast milk. Tell your healthcare provider if you are breastfeeding or plan to breastfeed. Your healthcare provider will advise you if you should stop breastfeeding or stop methazolamide.

Interactions

Does methazolamide interact with foods or drinks?

There are no known interactions between methazolamide and foods or drinks.

It is unknown if drinking alcohol will affect methazolamide. The risk of drowsiness or confusion may be increased if you drink alcohol while taking methazolamide.

Does methazolamide interact with other medicines (drug interactions)?

Always tell your healthcare provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using.

In particular, make sure that you discuss if you are using any of the following before taking methazolamide.

  • A corticosteroid, which is a medicine for certain inflammatory conditions
  • Aspirin, which is in many prescription and OTC products including those for pain, swelling, and fever

This may not be a complete list of medicines that can interact with methazolamide. Always check with your healthcare provider.

Does Methazolamide interact with other drugs you are taking?
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Overdose/Missed Dose

What should I do if I accidentally use too much methazolamide?

If you or someone else has used too much methazolamide, get medical help right away, call 911, or contact a Poison Control center at 800-222-1222.

What should I do if I miss a dose of methazolamide?

If you miss a dose, take it as soon as you remember. If it is almost time for your next dose, skip the missed dose and only take the next dose. Do not take double or extra doses.

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