In the U.S.—

In Canada—

• Antifungal, systemic

Griseofulvin (gri-see-oh-FUL-vin) belongs to the group of medicines called antifungals. It is used to treat fungus infections of the skin, hair, fingernails, and toenails. This medicine may be taken alone or used along with medicines that are applied to the skin for fungus infections.

Griseofulvin is available only with your doctor's prescription, in the following dosage forms:

Oral
• Capsules (U.S.)
• Suspension (U.S.)
• Tablets (U.S. and Canada)

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 griseofulvin, the following should be considered:

Allergies—Tell your doctor if you have ever had any unusual or allergic reaction to penicillins, penicillamine (e.g., Cuprimine), or griseofulvin. Also tell your health care professional if you are allergic to any other substances, such as foods, preservatives, or dyes.

Diet—Griseofulvin is absorbed best when it is taken with a high fat meal, such as a cheeseburger, whole milk, or ice cream. Tell your doctor if you are on a low-fat diet.

Pregnancy—Griseofulvin should not be used during pregnancy. The birth of twins that were joined together has been reported, although rarely, in women who took griseofulvin during the first 3 months of pregnancy. In addition, studies in rats and dogs have shown that griseofulvin causes birth defects and other problems.

Breast-feeding—It is not known if griseofulvin is excreted in breast milk. However, griseofulvin has not been reported to cause problems in nursing babies.

Children—This medicine has been tested in a limited number of children 2 years of age or older. In effective doses, the medicine has not been shown to cause different side effects or problems than it does in adults.

Older 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 griseofulvin 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.

Other medicines—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. When you are taking griseofulvin, it is especially important that your health care professional knows if you are taking any of the following:

• Anticoagulants (blood thinners)—Griseofulvin may decrease the effectiveness of anticoagulants in some patients

• Oral contraceptives (birth control pills) containing estrogen—Griseofulvin may decrease the effectiveness of birth control pills, which may result in breakthrough bleeding and unwanted pregnancies

• Liver disease—Griseofulvin may on rare occasion cause side effects affecting the liver

• Lupus erythematosus or lupus-like diseases—Griseofulvin may worsen lupus symptoms in patients who have lupus erythematosus or lupus-like diseases

• Porphyria—Griseofulvin may increase attacks of porphyria in patients with acute intermittent porphyria

Griseofulvin is best taken with or after meals, especially fatty ones (for example, whole milk or ice cream). This lessens possible stomach upset and helps to clear up the infection by helping your body absorb the medicine better. However, if you are on a low-fat diet, check with your doctor.

For patients taking the oral liquid form of griseofulvin :

• 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.

To help clear up your infection completely, keep taking this medicine for the full time of treatment, even if you begin to feel better after a few days. Do not miss any doses.

Dosing—

The dose of griseofulvin 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 griseofulvin. If your dose is different, do not change it unless your doctor tells you to do so.

The number of capsules or tablets or teaspoonfuls of suspension 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 taking griseofulvin.

• For microsize capsules, tablets, and suspension:
  • Adults and teenagers:
    • Treatment of fungus infections of the feet and nails—500 milligrams (mg) every twelve hours.
    • Treatment of fungus infections of the scalp, skin, and groin—250 mg every twelve hours; or 500 mg once a day.
  • Children:
    • Treatment of fungus infections—Dose is based on body weight. The usual dose is 5 mg per kilogram (kg) (2.3 mg per pound) of body weight every twelve hours; or 10 mg per kg (4.6 mg per pound) of body weight once a day.
• For ultramicrosize tablets:
  • Adults and teenagers:
    • Treatment of fungus infections of the feet and nails—250 to 375 mg every twelve hours.
    • Treatment of fungus infections of the scalp, skin, and groin—125 to 187.5 mg every twelve hours; or 250 to 375 mg once a day.
  • Infants and children up to 2 years of age:
    • Treatment of fungus infections—Use and dose must be determined by your doctor.
  • Children 2 years of age and over:
    • Treatment of fungus infections—Dose is based on body weight. The usual dose is 2.75 to 3.65 mg per kg (1.25 to 1.7 mg per pound) of body weight every twelve hours; or 5.5 to 7.3 mg per kg (2.5 to 3.3 mg per pound) of body weight once a day.

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.

Storage—

To store this medicine:

• Keep out of the reach of children.
• Store away from heat and direct light.
• Do not store the capsule or tablet form of this medicine in the bathroom, near the kitchen sink, or in other damp places. Heat or moisture may cause the medicine to break down.
• Keep the oral liquid form of this medicine from freezing.
• Do not keep outdated medicine or medicine no longer needed. Be sure that any discarded medicine is out of the reach of children.

Your doctor should check your progress at regular visits to make sure that griseofulvin does not cause unwanted effects.

Oral contraceptives (birth control pills) containing estrogen may not work properly if you take them while you are taking griseofulvin. Unplanned pregnancies may occur. You should use a different or additional means of birth control while you are taking griseofulvin and for one month after stopping griseofulvin. If you have any questions about this, check with your health care professional.

Griseofulvin may increase the effects of alcohol. If taken with alcohol it may also cause fast heartbeat, flushing, increased sweating, or redness of the face. Therefore, if you have this reaction, do not drink alcoholic beverages while you are taking this medicine, unless you have first checked with your doctor.

This medicine may cause some people to become dizzy or less alert than they are normally. Make sure you know how you react to this medicine before you drive, use machines, or do other things that could be dangerous if you are dizzy or are not alert. If these reactions are especially bothersome, check with your doctor.

Griseofulvin may cause your skin to be more sensitive to sunlight than it is normally. Exposure to sunlight, even for brief periods of time, may cause a skin rash, itching, redness or other discoloration of the skin, or a severe sunburn. When you begin taking this medicine:

• Stay out of direct sunlight, especially between the hours of 10:00 a.m. and 3:00 p.m., if possible.
• Wear protective clothing, including a hat. Also, wear sunglasses.
• Apply a sun block product that has a skin protection factor (SPF) of at least 15. Some patients may require a product with a higher SPF number, especially if they have a fair complexion. If you have any questions about this, check with your health care professional.
• Apply a sun block lipstick that has an SPF of at least 15 to protect your lips.
• Do not use a sunlamp or tanning bed or booth.

If you have a severe reaction from the sun, check with your doctor.

Griseofulvin has been shown to cause liver and thyroid tumors in some animals. You and your doctor should discuss the good this medicine will do, as well as the risks of taking it.

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

• Less common
  • Confusion;  increased sensitivity of skin to sunlight;  skin rash, hives, or itching;  soreness or irritation of mouth or tongue 
  
  

• Rare
  • Numbness, tingling, pain, or weakness in hands or feet;  sore throat and fever;  yellow eyes or skin 
  
  

Other 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. However, check with your doctor if any of the following side effects continue or are bothersome:

• More common
  • Headache 
  
  

• Less common
  • Diarrhea;  dizziness;  nausea or vomiting;  stomach pain;  trouble in sleeping;  unusual tiredness 
  
  

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