In the U.S.—

In Canada—

• Antihypertensive

Minoxidil (mi-NOX-i-dill) belongs to the general class of medicines called antihypertensives. It is used to treat high blood pressure (hypertension).

High blood pressure adds to the workload of the heart and arteries. If it continues for a long time, the heart and arteries may not function properly. This can damage the blood vessels of the brain, heart, and kidneys, resulting in a stroke, heart failure, or kidney failure. High blood pressure may also increase the risk of heart attacks. These problems may be less likely to occur if blood pressure is controlled.

Minoxidil works by relaxing blood vessels so that blood passes through them more easily. This helps to lower blood pressure.

Minoxidil has other effects that could be bothersome for some patients. These include increased hair growth, weight gain, fast heartbeat, and chest pain. Before you take this medicine, be sure that you have discussed the use of it with your doctor.

Minoxidil is being applied to the scalp in liquid form by some balding men to stimulate hair growth. However, improper use of liquids made from minoxidil tablets can result in minoxidil being absorbed into the body, where it may cause unwanted effects on the heart and blood vessels.

Minoxidil is available only with your doctor's prescription, in the following dosage form:

Oral
• 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 minoxidil, the following should be considered:

Allergies—Tell your doctor if you have ever had any unusual or allergic reaction to minoxidil. Also tell your health care professional if you are allergic to any other substances, such as foods, preservatives, or dyes.

Pregnancy—Minoxidil has not been studied in pregnant women. However, there have been reports of babies born with extra thick or dark hair on their bodies after the mothers took minoxidil during pregnancy. Discuss this possible effect with your doctor.

Studies in rats found a decreased rate of conception, and studies in rabbits at 5 times the human dose have shown a decrease in successful pregnancies. Minoxidil did not cause birth defects in rats or rabbits.

Breast-feeding—Although minoxidil passes into breast milk, it has not been reported to cause problems in nursing babies.

Children—Although there is no specific information comparing use of minoxidil in children with use in other age groups, this medicine is not expected to cause different side effects or problems in children than it does in adults.

Older adults—Elderly patients may be more sensitive to the effects of minoxidil. In addition, minoxidil may reduce tolerance to cold temperatures in elderly patients.

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 taking minoxidil it is especially important that your health care professional know if you are taking any of the following:

• Guanethidine (e.g., Ismelin) or
• Nitrates (medicine for angina)—Severe lowered blood pressure may occur

• Angina (chest pain)—Minoxidil may make this condition worse

• Heart attack or stroke (recent)—Lowering blood pressure may make problems resulting from heart attack or stroke worse

• Heart or blood vessel disease—Minoxidil can cause fluid buildup, which can cause problems

• Kidney disease—Effects may be increased because of slower removal of minoxidil from the body

• Pheochromocytoma—Minoxidil may cause the tumor to be more active

In addition to the use of the medicine your doctor has prescribed, treatment for your high blood pressure may include weight control and care in the types of foods you eat, especially foods high in sodium. Your doctor will tell you which of these are most important for you. You should check with your doctor before changing your diet.

Many patients who have high blood pressure will not notice any signs of the problem. In fact, many may feel normal. It is very important that you take your medicine exactly as directed and that you keep your appointments with your doctor even if you feel well.

Remember that minoxidil will not cure your high blood pressure but it does help control it. Therefore, you must continue to take it as directed if you expect to lower your blood pressure and keep it down. You may have to take high blood pressure medicine for the rest of your life . If high blood pressure is not treated, it can cause serious problems such as heart failure, blood vessel disease, stroke, or kidney disease.

To help you remember to take your medicine, try to get into the habit of taking it at the same time each day.

This medicine is usually given together with certain other medicines. If you are using a combination of drugs, make sure that you take each medicine at the proper time and do not mix them. Ask your health care professional to help you plan a way to remember to take your medicines at the right time.

Dosing—

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

• For oral dosage forms (tablets):
  • Adults and children over 12 years of age: 5 to 40 milligrams taken as a single dose or in divided doses.
  • Children up to 12 years of age: 200 micrograms to 1 milligram per kilogram of body weight a day to be taken as a single dose or in divided doses.

Missed dose—

If you miss a dose of this medicine and remember it within a few hours, take it when you remember. However, if you do not remember until the next day, 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 in the bathroom, near the kitchen sink, or in other damp places. Heat or moisture may cause the medicine to break down.
• Do not keep outdated medicine or medicine no longer needed. Be sure that any discarded medicine is out of the reach of children.

It is important that your doctor check your progress at regular visits to make sure that this medicine is working properly.

Ask your doctor about checking your pulse rate before and after taking minoxidil. Then, while you are taking this medicine, check your pulse regularly while you are resting. If it increases by 20 beats or more a minute, check with your doctor right away.

While you are taking minoxidil, weigh yourself every day. A weight gain of 2 to 3 pounds (about 1 kg) in an adult is normal and should be lost with continued treatment. However, if you suddenly gain 5 pounds (2 kg) or more (for a child, 2 pounds [1 kg] or more) or if you notice swelling of your feet or lower legs, check with your doctor right away.

Do not take other medicines unless they have been discussed with your doctor. This especially includes over-the-counter (nonprescription) medicines for appetite control, asthma, colds, cough, hay fever, or sinus problems, since they may tend to increase your blood pressure.

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 immediately if any of the following side effects occur:

• More common
  • Fast or irregular heartbeat;  weight gain (rapid) of more than 5 pounds (2 pounds in children) 
  
  

• Less common
  • Chest pain;  shortness of breath 
  
  

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

• More common
  • Bloating;  flushing or redness of skin ;  swelling of feet or lower legs 
  
  

• Less common
  • Numbness or tingling of hands, feet, or face 
  
  

• Rare
  • Skin rash and itching 
  
  

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
  • Increase in hair growth, usually on face, arms, and back 
  
  

• Less common or rare
  • Breast tenderness in males and females;  headache 
  
  

This medicine causes a temporary increase in hair growth in most people. Hair may grow longer and darker in both men and women. This may first be noticed on the face several weeks after you start taking minoxidil. Later, new hair growth may be noticed on the back, arms, legs, and scalp. Talk to your doctor about shaving or using a hair remover during this time. After treatment with minoxidil has ended, the hair will stop growing, although it may take several months for the new hair growth to go away.

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