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Primary Periodic Paralysis is a rare neuromuscular condition

You Are Not Alone: The Power of Education, Advocacy, & Support

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  • Watch our program from the 2020 Periodic Paralysis Association (PPA) virtual conference, where we brought doctors and patients together to speak on topics surrounding PPP. These topics included the diagnosis and impact of PPP, management of PPP, and the support Xeris CareConnection can provide to those living with PPP.

What is Primary Periodic Paralysis (PPP)?

PPP is a rare condition that affects your muscles and causes episodes of muscle weakness and/or temporary paralysis.1,2 Episodes of weakness or paralysis usually start happening in childhood, before age 20. Some people begin having attacks as early as age 2 or even younger.3 PPP episodes (muscle weakness or temporary paralysis) can vary in how often they occur, how severe they are, and in how long they last. A study found that most episodes range from 30 minutes to several hours. For some patients, episodes can last for days.1*

What causes Primary Periodic Paralysis?

PPP is usually inherited, meaning that it is passed down from a parent to a child.4 However, not having the genetic abnormality does not mean you don’t have PPP if you have the signs and symptoms of the condition.2 PPP attacks cause symptoms that affect many parts of the body and can vary in how severe they are and how long they last.1,2
Learn more about KEVEYIS and how it may be right for you.
Primary Periodic Paralysis is usually inherited, meaning it can be passed down from a parent to child.

How is PPP diagnosed?

Incorrect diagnoses and delays in diagnosis are common because symptoms can mimic those of more common conditions.1,2 If PPP is suspected, your doctor will usually review your medical history and your family medical history, then perform a physical exam and possibly blood tests.2 As PPP is typically inherited, your doctor may also recommend genetic testing.
  • There is a 50% chance of having PPP if one of your parents has PPP4
  • However, about 30% of people with PPP do not have one of the common genetic mutations associated with this condition2
If the test results come back negative, your doctor may perform one or more of the following tests, including1,5:
Electrocardiogram (ECG/EKG)1
Electromyography (EMG)2
Compound muscle action potential (CMAP)5

Subtypes of PPP

There are several subtypes of PPP. What makes them different from one another is the level of potassium in the blood during an episode, what happens during the episode, what triggers the episode, and which genes are involved since multiple genes can cause PPP. There are six genes which may be involved in one or more of the subtypes.1,2,5 The most common subtypes of PPP are:
  • Hyperkalemic [hai-pr-kuh-lee-muhk]—usually associated with high potassium levels during an episode2
  • Hypokalemic [hai-po-kuh-lee-muhk]—usually associated with low potassium levels during an episode2Some people have episodes that are similar to hyperkalemic PPP and hypokalemic PPP, but their potassium levels are normal. This is called normokalemic [nor-mo-kuh-lee-muhk] PPP.5
  • Paramyotonia congenita [pa-ruh-mai-oh-toe-nee-uh kuhn-jeh-nuh-ta] (PMC)—causes muscle stiffness and may be associated with normal or high potassium levels during an episode1,6
  • Andersen-Tawil syndrome (ATS)—causes muscle weakness, changes in heartbeat, and distinct skeletal features. It is associated with low, normal, or high potassium levels during an episode2,7

*Exploratory study in 94 genetically diagnosed men and women ages 19-84, designed to create an evidence-based comprehensive characterization of hyperkalemic periodic paralysis (hyperPP).



Indication and Important Safety Information

What is KEVEYIS?

KEVEYIS (pronounced keh-VAY-iss) (dichlorphenamide) is a prescription drug used to treat primary hyperkalemic periodic paralysis, primary hypokalemic periodic paralysis, and other similar diseases.

What should you tell your healthcare provider before taking KEVEYIS?

Tell your doctor if you are allergic to dichlorphenamide or other sulfa drugs; if you take high doses of aspirin, or if you have lung or liver disease; if you are pregnant, plan to become pregnant, or are breastfeeding or plan to breastfeed.

What should you know about KEVEYIS?

  • Severe allergic and other reactions have happened with sulfonamides (drugs such as KEVEYIS) and have sometimes been fatal. Stop taking KEVEYIS at the first sign of skin rash, swelling, difficulty breathing, or any other unexpected side effect or reaction, and call 911 right away.
  • Tell your healthcare provider if you take aspirin or if another healthcare provider instructs you to begin taking aspirin. High doses of aspirin should not be taken with KEVEYIS.
  • KEVEYIS can cause your body to lose potassium, which can lead to heart problems. Your healthcare provider will measure the potassium levels in your blood before you start treatment and at certain times during treatment.
  • Tell your healthcare provider about all other prescription and over-the-counter medicines you take, including supplements, as some medicines can interact with KEVEYIS.
  • While taking KEVEYIS, your body may produce too much acid or may not be able to remove acid from the body. Your healthcare provider may run tests on a regular basis to check for signs of acid buildup.
  • KEVEYIS may increase your risk of falling. Tell your healthcare provider right away if you experience a fall while taking KEVEYIS.
  • The risks of falls and acid buildup are greater in elderly patients.
  • It is not known whether KEVEYIS is safe or effective for people younger than 18 years of age.

What are the most common side effects with KEVEYIS?

The most common side effects are a feeling of numbness, tingling or burning (“pins and needles”) in the toes, feet, hands or fingers; trouble with memory or thinking; feeling confused; and unpleasant taste in the mouth.

These are not all of the possible side effects of KEVEYIS. Call your healthcare provider for medical advice about side effects. You are encouraged to report negative side effects of prescription drugs to the FDA. Visit or call 1-800-FDA-1088.


  1. Charles G, Zheng C, Lehmann-Horn F, Jurkat-Rott K, Levitt J. Characterization of hyperkalemic periodic paralysis: a survey of genetically diagnosed individuals. J Neurol. 2013;260:2606-2613.
  2. Statland JM, Fontaine B, Hanna MG, et al. Review of the diagnosis and treatment of periodic paralysis. Muscle Nerve. 2018;57:522-530.
  3. Cavel-Greant D, Lehmann-Horn F, Jurkat-Rott K. The impact of permanent muscle weakness on quality of life in periodic paralysis: a survey of 66 patients. Acta Myol. 2012;31:126-133.
  4. Fontaine B, Phillips LH 2nd. A newly approved drug for a rare group of diseases: dichlorphenamide for periodic paralysis. Neurology. 2016;86:1366-1367.
  5. Weber F. Hyperkalemic Periodic Paralysis. In: Adam MP, Feldman J, Mirzaa GM, et al., eds. GeneReviews®. Seattle (WA): University of Washington, Seattle; July 18, 2003.
  6. National Institutes of Health. Paramyotonia congenita. Available at: Accessed March 22, 2024
  7. National Institutes of Health. Andersen-Tawil syndrome. Available at: Accessed March 22, 2024