Dichlorphenamide (Oral)

Dichlorphenamide is also known under US brand name Keveyis. This drug is used in the treatment of a certain inherited condition that causes attacks of muscle weakness or loss of muscle movement that comes and goes. This drug is taken orally via a tablet.


Dichlorphenamide is a drug used in the treatment of inherited muscle disorders, such as primary hypokalemic periodic paralysis, primary hyperkalemic periodic paralysis, and other related variants. This medication is a carbonic anhydrase inhibitor. This medicine is only available via prescription from your doctor and is available in the dosage form of a tablet.

Condition(s) treated?

  • Familial Hyperkalemic Periodic Paralysis

Type of medicine?

  • Tablet

Side Effects

Alongside the needed effects of dichlorphenamide, the consumption of this drug may produce some unwanted side effects. Not all of these side effects may occur, however, in some cases they may require medical attention.

Speak with a medical professional or doctor immediately if you suffer from any of the following side effects when taking dichlorphenamide:

Incidence not known

  • Black, tarry stools

Seek emergency help if you suffer from any of the following signs of overdose occur when taking dichlorphenamide:

Symptoms of overdose

  • Bloody, black, or tarry stools
  • Shakiness in the arms, legs, hands, or feet

Some side effects that occur with dichlorphenamide may not require any medical attention. These side effects usually begin to reduce with time as your body begins adjusting to the medication. If they are bothering your daily life, you should contact your local pharmacist or doctor for advice on ways to prevent to reduce the intensity of these side effects.

More common side effects

  • Change in taste

Incidence not known

  • Decreased awareness or responsiveness

Severe sleepiness

  • Problems with memory

Remember you can report all side effects to the FDA on 1-800-FDA-1088, regardless of severity. You may experience some side effects that are not listed above. If you experience any strange or out of the ordinary, then seek medical advice from a healthcare professional or your doctor. Don't suffer in silence.


The final dose of any medication will depend upon a number of different factors. These include your age, weight and height, the current medications you are taking, the severity of your condition and how you respond to initial treatment. Do not alter doses without prior consultation with your doctor or a healthcare professional.

Typical Adult Dose for Primary Periodic Paralysis

An initial dose of 50 mg taken orally twice a day. The initial dose can be increased or decreased based on individualized responses, at weekly intervals. This can be done sooner in case of adverse reactions. The maximum dose is 200 mg orally each day.

  • Primary hypokalemic periodic paralysis, primary hyperkalemic periodic paralysis, and related variants are a heterogeneous group of conditions. The response to this drug varies. Prescribers should evaluate patient response to this drug after two months of treatment to decide whether this therapy should be discontinued.

If you miss a dose of this medicine, take it as soon as you remember. However, if it's close to the scheduled time of your next dose, you should skip this dose and revert back to your original dosing schedule. Don't double your doses.


Drug interactions can cause serious side effects and reduce the usefulness of each drug. To help limit the chance of side effects you should give your doctor or a healthcare professional a full list of all the drugs and medications you are currently taking. Your list should include all prescription and non-prescription drugs, all vitamins and herbal products and remedies. It's a good idea to also give your doctor a list of any other medical conditions you are currently suffering from and anything you have suffered from in the past. Also, include any conditions that run in your family.

The use of this medication with any of the following medications isn't recommended. Your doctor may decide to avoid treatment with this drug or alter the other medicines you are taking.

  • Aspirin

There are over 359 drugs that interact with dichlorphenamide. Some of the drugs are listed below, but this list is not complete.

  • Acetazolamide

Other Medical Problems

The presence of other medical conditions can affect the use of this medication. Remember to inform your doctor or a healthcare professional if you have any other medical conditions, especially:

  • Hyperchloremic metabolic acidosis



Let your doctor know if you've got unusual or allergic reaction to this medication or any other medications. You should also let your doctor or a healthcare professional know if you suffer from any other allergies including to dyes, foods, animals or preservatives.

Use in pediatric population

Studies have not been conducted on the relationship of age to the effects of dichlorphenamide on the pediatric population. Therefore efficacy and safety have not been established.

Use in geriatric population

Studies conducted to date have not indicated any geriatric-specific issues that could limit the effectiveness of dichlorphenamide in the older population. However, older patients are more likely to suffer from metabolic acidosis or experience falls, which may require an extra degree of caution in those receiving dichlorphenamide.

Use in pregnancy and during breastfeeding

This drug is under FDA pregnancy category C. It is currently unknown whether this medication can harm an unborn infant. Let your doctor know if you currently pregnant or hope to be pregnant in the near future.

It is currently unknown whether dichlorphenamide can pass into breast milk or if it could affect a nursing infant Let your doctor know if you are breastfeeding when using this medication.

Don't use this medication in conjunction with high-dose aspirin as it can produce unwanted side effects.

This medication may cause a serious allergic reaction, including anaphylaxis. This can be life-threatening and requires urgent medical attention. Check with your doctor immediately if you have to peel, blistering or red skin rash, fever with or without chills, lower back or side pain, itching skin, painful or difficult urination, sores, sore throat, ulcers, or white spots on the lips or in the mouth, unusual bruising or bleeding, or yellow skin or eyes.

Inform your doctor or a healthcare professional if you have convulsions, increased thirst, dry mouth, muscle pain or cramps, nausea or vomiting, tingling or numbness in the feet, hands or lips, or uneven heartbeat. These may be signs of hypokalemia.

This medication may cause some people to feel more tired or drowsy than they are normally. Ensure you know how you react to this medication before you use machinery, drive or do anything else that requires you to be alert.

Older adults may be at greater risk for low bicarbonate levels while using this drug.


This medication needs to be stored in a closed container at room temperature. It also needs to be kept away from moisture, heat, and direct light. Do not let medication freeze. Keep out of the reach of children and do not keep medication you no longer need or is outdated. Speak with your healthcare professional about how you should dispose of any medication you do not use carefully.


When used correctly, dichlorphenamide is successful in treating conditions that cause attacks of muscle weakness or loss of muscle movement that come and go. Limit alcoholic beverages and speak to your doctor if you use marijuana when using this drug. Due to the high amount of interactions possible with this drug it's important you let your doctor know of any medications you are currently taking. It's best to speak with your doctor if you are pregnant or breastfeeding before you begin taking this medication. Take this medication directly as your doctor has instructed. Don't take more of it, or take it more often and do not take it for a longer time than your doctor has instructed. If you do, you may increase your chances of serious side effects significantly. Efficacy and safety have not been established in patients younger than eighteen years of age. It's recommended that patients should notify their doctor or a healthcare professional if they experience a worsening of side effects or symptoms of periodic paralysis.