Xywav is a central nervous system depressant. It is used to treat cataplexy (sudden loss of muscle strength) or to reduce daytime sleepiness caused by narcolepsy. For these conditions, Xywav is for use in adults and children at least 7 years old.

Xywav is also used in adults to reduce daytime sleepiness caused by idiopathic hypersomnia (an uncommon chronic sleep disorder that causes daytime sleepiness even after a good night's sleep).

Xywav contains GHB, a known street drug of abuse. Because of the potential for abuse and serious side effects, Xywav is available only from a certified pharmacy under a special program. You must be registered in the program and understand the risks and benefits of calcium, magnesium, potassium, and sodium oxybates.

Xywav may also be used for purposes not listed in this medication guide.

This medicine can cause breathing problems, seizure, loss of consciousness, or death, especially if you also use other sleep medicine, opioid pain medicine, a muscle relaxer, or medicine for anxiety, depression, mental illness, or seizures.

Do not drink alcohol together with Xywav.

The morning after taking this medicine, wait at least 6 hours or until you are fully awake before you do anything that requires you to be awake and alert.

May be habit-forming. Misuse can cause addiction, overdose, or death. Keep the medication in a place where others cannot get to it.

Follow all directions on your prescription label and read all medication guides or instruction sheets. Xywav can cause severe drowsiness and can slow or stop your breathing, even at regular doses or if you are also taking stimulant medicine. Use your medicine exactly as directed.

Xywav may be habit-forming. Misuse can cause addiction, overdose, or death. Keep the medication in a place where others cannot get to it. Selling or giving away this medicine is against the law. Do not allow anyone else to use this medicine.

Xywav is taken as 1 nightly dose, or as 2 doses (once at bedtime and again 2.5 to 4 hours later). Do not take Xywav within 2 hours after eating.

Xywav must be mixed with 2 ounces (1/4 cup) of water in the child-resistant dosing cups provided with the medication.

If you take 2 nightly doses, prepare both doses while you are getting ready for bed. Place the second dose in a secure location next to your bed so you can take it without getting up. You may need to set an alarm to awaken for the second dose.

This medicine works quickly. Most people fall asleep within 5 to 15 minutes.

Take Xywav only while you are sitting in bed ready for sleep. Some people have fallen asleep while standing or getting up from bed, which has caused injuries serious enough to need treatment in a hospital.

Do not allow a child to use this medicine without adult supervision.

Do not change your dose or stop using Xywav suddenly, or you could have unpleasant withdrawal symptoms. Ask your doctor how to safely stop using this medicine.

Store at room temperature away from moisture and heat. Keep your medicine in a place where no one can use it improperly.

Throw away any dose not used within 24 hours after mixing.

Do not keep leftover Xywav liquid. Ask your pharmacist where to locate a drug take-back disposal program. If there is no take-back program, pour any unused liquid medicine down a sink drain.

Do not drink alcohol or take other sleep medicines together with Xywav. Dangerous side effects or death could occur.

Do not give Xywav to anyone with a rare metabolic disorder called succinic semialdehyde dehydrogenase deficiency (which can cause mental or physical impairment).

Tell your doctor if you have ever had:

• breathing problems;

• snoring, or sleep apnea (breathing stops during sleep);

• depression or suicidal thoughts;

• psychosis or unusual behaviors (anxiety, agitation, paranoia, aggression, hallucinations);

• liver disease; or

• a drug addiction.

Tell your doctor if you are pregnant or breastfeeding.

Not approved for use by anyone younger than 7 years old with narcolepsy. Not approved for use by anyone younger than 18 years old with idiopathic hypersomnia.

Skip the missed dose and use your next dose at the regular time. Do not use two doses at one time.

Take Xywav only during your normal sleeping hours (wait at least 2 hours after eating).

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222. An overdose of Xywav can be fatal.

Overdose symptoms may include sweating, vomiting, severe confusion, loss of balance or coordination, or seizure (convulsions).

Do not drink alcohol. Dangerous side effects or death could occur.

Do not take other sleep medicines together with Xywav.

Xywav will cause drowsiness and can impair your thinking or reactions. You may still feel sleepy the morning after taking this medicine. Wait at least 6 hours or until you are fully awake before you drive, operate machinery, pilot an airplane, or do anything that requires you to be awake and alert.

Get emergency medical help if you have signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Calcium, magnesium, potassium, and sodium oxybates may cause serious side effects. Call your doctor at once if you have:

• weak or shallow breathing, breathing that stops for short periods of time;

• severe drowsiness, feeling light-headed;

• sleepwalking (may result in an injury), waking and confused behavior at night;

• a seizure;

• depression, anxiety, unusual or unpleasant thoughts;

• feelings of low self-worth, loss of interest in things you once enjoyed;

• confusion, paranoia, hallucinations (seeing or hearing things);

• increased tiredness, trouble concentrating; or

• suicidal thoughts or actions.

Common side effects of calcium, magnesium, potassium, and sodium oxybates may include:

• sleepwalking, talking or eating in your sleep;

• new sleep problems, strange dreams, night terrors;

• drowsiness, dizziness, tiredness, headache;

• tremors, anxiety;

• dry mouth, nausea, vomiting, diarrhea;

• weight loss; or

• bedwetting (in children).

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Fatal side effects can occur if you take Xywav with other drugs that cause drowsiness or slow your breathing. Ask your doctor before taking cold or allergy medicine, opioid medication, sedatives, muscle relaxers, seizure medicine, or medicine for depression, anxiety, or mental illness.

If you start or stop taking divalproex (Depakote), your doctor may need to adjust your Xywav dose.

Other drugs may affect Xywav, including prescription and over-the-counter medicines, vitamins, and herbal products. Tell your doctor about all other medicines you use.