Dosing Instructions for Famotidine, Hydroxyzine, Xifaxan, and Mylanta/Tums
Famotidine (Morning Dose)
Take famotidine 20 mg once daily in the morning for gastrointestinal protection. 1, 2
- Famotidine reaches peak plasma concentrations in 1-3 hours after oral administration and provides antisecretory activity lasting 10-12 hours 2
- The 20 mg dose is effective for maintenance therapy of peptic ulcer disease and prevention of gastric mucosal damage 3, 4
- Can be taken with or without food 2
- For patients with renal impairment, dose adjustment may be necessary as famotidine is eliminated primarily through the kidneys (approximately 70%) 2
Hydroxyzine (Evening Dose)
Take hydroxyzine at bedtime (pm) as prescribed by your physician for its antihistamine and sedative effects.
- Timing at bedtime takes advantage of the sedating properties while minimizing daytime drowsiness
- Avoid alcohol and other CNS depressants when taking hydroxyzine
- May cause dry mouth, which can be managed with sugar-free gum or frequent sips of water
Xifaxan (Rifaximin)
The dosing of Xifaxan depends on your specific gastrointestinal condition: 5
For Travelers' Diarrhea:
For Hepatic Encephalopathy Prevention:
For Irritable Bowel Syndrome with Diarrhea (IBS-D):
- Take one 550 mg tablet three times daily for 14 days 5
- If symptoms recur, you can be retreated up to 2 times with the same regimen 5
- Can be taken with or without food 5
Important: If diarrhea worsens or persists for more than 24-48 hours, or if you develop fever or bloody stools, discontinue Xifaxan and contact your healthcare provider immediately. 5
Mylanta/Tums (Antacids)
Take antacids as needed for breakthrough heartburn or acid reflux symptoms, with the following timing considerations:
- Take antacids at least 2 hours apart from famotidine to avoid interference with absorption
- For optimal effect, take 1-3 hours after meals and at bedtime when acid secretion is highest
- Do not exceed the maximum daily dose listed on the product label
- If you need antacids more than twice weekly despite famotidine, contact your healthcare provider as this may indicate inadequate acid suppression
Special Considerations for Diabetes Insipidus
For patients with diabetes insipidus, maintain adequate fluid intake and monitor for signs of dehydration, especially during acute illness: 6
- During episodes of vomiting, diarrhea, or decreased fluid intake, contact your healthcare provider immediately 6
- If taking desmopressin (DDAVP) for diabetes insipidus, continue as prescribed and adjust fluid intake to avoid water intoxication 7
- Monitor for symptoms requiring medical attention: reduced consciousness, inability to keep fluids down, or significant changes in urine output 6
Critical Timing and Drug Interaction Considerations
- Famotidine should be taken in the morning to provide daytime acid suppression while allowing some acid secretion overnight for calcium absorption
- Hydroxyzine at bedtime minimizes daytime sedation and may help with sleep
- Space antacids at least 2 hours from other medications to prevent absorption interference
- If you develop new diarrhea after starting or during Xifaxan therapy, contact your healthcare provider to evaluate for Clostridium difficile infection 5
When to Seek Medical Attention
Contact your healthcare provider immediately if you experience: 6, 5
- Reduced level of consciousness or new confusion 6
- Vomiting more than 4 times in 12 hours or inability to keep fluids down 6
- Fever with temperature >101°F (38°C) on two measurements 6
- Diarrhea that worsens or persists beyond 24-48 hours on Xifaxan 5
- Signs of severe dehydration: extreme thirst, decreased urine output, dizziness when standing 6