Description and Brand Names

Drug information provided by: Merative, Micromedex®

US Brand Name

  1. ME-500


Racemethionine is used to make the urine more acidic. Making the urine more acidic helps to relieve skin irritation in incontinent (loss of bladder control) adults and diaper rash in infants. This medicine also helps to control strong urine odor.

Racemethionine is available only with your doctor's prescription.

Before Using

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For this medicine, the following should be considered:


Tell your doctor if you have ever had any unusual or allergic reaction to this medicine or any other medicines. Also tell your health care professional if you have any other types of allergies, such as to foods, dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.


This medicine has been tested in children and, in effective doses, has not been shown to cause different side effects or problems than it does in adults.


Many medicines have not been studied specifically in older people. Therefore, it may not be known whether they work exactly the same way they do in younger adults. Although there is no specific information comparing use of racemethionine in the elderly with use in other age groups, this medicine is not expected to cause different side effects or problems in older people than it does in younger adults.

Drug Interactions

Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. Tell your healthcare professional if you are taking any other prescription or nonprescription (over-the-counter [OTC]) medicine.

Other Interactions

Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. Discuss with your healthcare professional the use of your medicine with food, alcohol, or tobacco.

Other Medical Problems

The presence of other medical problems may affect the use of this medicine. Make sure you tell your doctor if you have any other medical problems, especially:

  • Acidosis (metabolic) or
  • Liver disease—Use of racemethionine may make these conditions worse

Proper Use

You should not take more of this medicine, or take it more often, than your doctor ordered. You should also make sure that you get enough protein in your diet. This is especially important in infants. Infants who get too much racemethionine and not enough protein may not gain weight as they should. If you have any questions about this, ask your health care professional.

Take racemethionine with, or just after, meals.

For patients taking racemethionine capsules:

  • If you are unable to swallow the capsule, the contents may be added to juice, water, or warm milk or infant formula.

For patients taking racemethionine oral solution:

  • Use a specially marked measuring spoon or other device to measure each dose accurately. The average household teaspoon may not hold the right amount of liquid.

Make certain your health care professional knows if you are on any special diet, such as a low-protein diet.


The dose of this medicine will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

  • For making urine more acidic:
    • For oral dosage form (capsules):
      • Adults and teenagers—The usual dose is 200 milligrams (mg) three or four times a day.
      • Children—The usual dose is the contents of 1 capsule (200 mg) added to a warm bottle of milk or formula in the evening, or added to a glass of juice or water.
    • For oral dosage form (oral solution):
      • Adults and children older than 14 months of age—The usual dose is 2⅔ teaspoonfuls (200 mg) three or four times a day.
      • Children 6 to 14 months of age—The usual dose is 1 teaspoonful (75 mg) four times a day for three to five days.
      • Children 2 to 6 months of age—The usual dose is 1 teaspoonful (75 mg) three times a day for three to five days.
      • Children up to 2 months of age—Dose must be determined by your doctor.
    • For oral dosage form (tablets):
      • Adults and teenagers—The usual dose is 500 mg three or four times a day.
      • Children—The capsule or oral solution is the recommended dosage form for this age group.

Missed Dose

If you miss a dose of this medicine, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses.


Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. Keep from freezing.

Keep out of the reach of children.

Do not keep outdated medicine or medicine no longer needed.


If your rash has not improved after 10 days, check with your doctor.

Side Effects

Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common

  1. Drowsiness
  2. nausea and vomiting

Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.

Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.