Minoxidil is used to control severely elevated blood pressure that is not manageable with a water pill and two other blood pressure pills on their own. After the first dose of minoxidil, blood pressure usually starts to go down within one-half hour.

High blood pressure increases the work of the heart and, if left for too long, may damage the heart, kidneys, brain, and blood vessels. Minoxidil works by relaxing the blood vessels so that the blood passes through them more easily. This helps to lower blood pressure.

Your doctor may choose to use this medication for other conditions. If you're unsure why you are taking this medication, contact your doctor.

Directions

The recommended starting dose of minoxidil is 5 mg given in two divided doses. If the desired blood pressure is not achieved, the doctor may increase the dose to 10 mg daily after three days, 20 mg daily after a further three days, and 40 mg daily after a further three days. These are only guidelines. Some people may require higher doses to keep their blood pressure under control. Many things can affect the dose of medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are taking the medication without consulting your doctor.

If you miss dose

If you miss a dose, take it as soon as remembered. If it is almost time for the next dose, skip the missed dose and carry on with your usual dosing schedule. Call the doctor if you miss two or more doses in a row.

Precautions

Minoxidil should not be taken by anyone with:

sensitivity or allergy to minoxidil or any ingredient of the product

a condition caused by a kind of tumor called a pheochromocytoma

Before taking minoxidil, tell your doctor of any medical conditions, including:

• angina (chest pain)
• history of heart attack or stroke
• heart disease or blood vessel disease
• kidney disease
• pheochromocytoma

Ask your doctor about checking your pulse rate before and after taking this medication.

Weigh yourself every day while taking minoxidil. If your weight increases by 5 pounds (2 pounds for children), call your doctor right away.

Side Effects

The following side effects have been reported with minoxidil but may go away during treatment as your body adjusts to it. If they persist or get worse, call your doctor.

• increase in hair growth, usually on face, arms, and back
• breast tenderness in males and females
• headache

Check with your doctor as soon as possible if you experience any of the following:

• bloating
• flushing or redness of skin
• swelling of feet or lower legs
• numbness or tingling of hands, feet, or face
• skin rash and itching

Check with your doctor immediately if any of the following side effects occur:

• fast or irregular heartbeat
• weight gain (rapid) of more than 5 pounds (2 pounds in children) - this means that your body is retaining more fluid than it should
• chest pain
• shortness of breath

Other side effects may occur that are not listed above. If you notice any other effects, check with your doctor.

Drug Interactions

There are several medications that minoxidil can affect, that affect how minoxidil works, or that can increase the occurrence of side effects:

• guanethidine
• nitrates
• any medication that has the effect of lowering blood pressure

Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications that you are taking. Also tell them about any supplements you take. Since caffeine, decongestants, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them. Depending on your specific circumstances, your doctor may want you to:

• stop taking one of the medications
• change one of the medications to another
• change how you are taking one or both of the medications
• leave everything as is

An interaction between two medications does not always mean that you must stop taking one of them. In many cases, interactions are intended or are managed by close monitoring. Speak to your doctor about how any drug interactions are being managed or should be managed.