Methyldopa (Intravenous, Oral)

By altering nerve pathways to help the blood vessels relax, oral or intravenous methyldopa makes blood flow easier - reducing blood pressure levels.


Oral or intravenous methyldopa is used in the treatment of high blood pressure, also known as hypertension.

The medication works by altering the way some of your nerve pathways work. Impulses along these pathways may need to be controlled, as doing this can relax the blood vessel. When blood vessels are relaxed, blood can pass through them much more easily, which in turn cuts your blood pressure levels.

High blood pressure is a serious condition which may cause you lots of problems if it is left untreated. For example, it raises the risk that you will suffer from a variety of serious problems, such as damage to blood vessels in major organs like the heart, the brain or the kidneys. This, in turn, creates a higher risk of you suffering from heart failure, a stroke or other major medical events.

In the USA, this medication has the brand name Aldomet which means you may see it referred to in this way in marketing materials, information booklets and more. This medication can be taken in a number of formats, including solution, tablet and suspension.

This medication is only available with a prescription from a physician.

Conditions Treated

Type Of Medicine

  • Antihypertensive

Side effects

As with lots of drugs, oral or intravenous methyldopa can cause a number of adverse health conditions while tackling the main problem of hypertension. These are known as side effects.

  • One side effect of taking this medication requires you to check in with your physician immediately, and that is if you experience fever just after beginning a course of this medication. This side effect is considered to be less common, but you may still experience it.
  • Other possible side effects of taking this medication do not require you to speak to a physician right away, but do require you to check in with them as soon as possible. One side effect in this category considered to be more common is experiencing swelling in your feet or lower leg region.

Side effects in this category which are considered less common include some mental health problems, like anxiety or depression, as well as problems like vivid dreams or nightmares. Other conditions are considered to be rare, including urination and excretion problems like dark urine, a pale hue to your stools and severe diarrhea. Stomach problems in this category include strong pain in the stomach region coupled with vomiting and nausea, as well as stomach cramps.

Other more miscellaneous problems which require a physician's attention as soon as possible include pain in your joints, a rash on your skin, an ongoing feeling of fatigue once you have taken this medication for a while, difficulty breathing, a speedier heartbeat than usual, a yellow hue to your skin or eyes, and more.

  • Other side effects do not necessarily require you to visit a physician or healthcare professional at all. This is because they are often just the body's natural response to taking the medication, and they will often go away by themselves and without any intervention. However, you should speak to your physician about them if they are causing you lots of problems or they do not go away.

Problems in this category considered to be more common include a dry mouth, a feeling of being drowsy, and experiencing headaches.

Problems considered to be less common but which may still occur include problems related to sexual function, such as a lower than usual ability to perform or a lower than usual interest in having sex.

Other problems in this category include experiencing a slower than usual heartbeat, a feeling of tingling or pain in the feet or hands, becoming lightheaded after standing up from a sitting down or lying down position, a stuffy nose and more.

In some patients, breast swelling or out of the ordinary production of milk may also occur.

  • There is no guarantee that you will or will not experience a particular side effect when taking oral or intravenous methyldopa. The experience of each patient can be different.

Remember, these lists of potential side effects are not exhaustive, so you should consult the full list which will usually be provided in the information booklet which comes with the drug.

You should speak to a healthcare professional if you have any concerns. They may be able to provide you with some tips on managing any side effects you do experience.

  • On some occasions, you may experience side effects which have not been listed here. If that happens, you should tell your physician.


When it comes to dosage amounts, frequency and other rules, you should always follow the instructions given to you by your physician. Your dosage may have been worked out on the basis of your individual medical circumstances, and as a result you should never take more or less than what your physician has instructed.

While some general information on dosages does exist, this is for information purposes only. It should never be substituted for the advice of a physician.

It is advised that you try to take this medication at the same time every day as this aids you in remembering to take it.

  • For adults who are taking oral or intravenous methyldopa in either its tablet or its suspension format to treat high blood pressure, the usual dosage will be between 250 milligrams (mg) to two grams each day. Usually, this will be divided up into a series of doses, between two and four per day.

For children taking this medication to treat high blood pressure, the dosage will usually be based on body weight. A physician will need to determine the exact dosage, but ordinarily 10 milligrams will be prescribed per every kilogram the child weighs (or 4.5 milligrams per pound of body weight) again divided into between two and four doses per day. In some cases, a physician will increase the dose if necessary.

  • Some patients will be required to take this medication in intravenous, or injection, format. For those adults taking this medication in this way to treat high blood pressure, the usual dosage will be between 250 to 500 milligrams of the medication mixed in to 100 millilitres of a 5% dextrose solution. This will generally be injected into a vein once in each six hour interval as is required.
  • In the event that you miss a dose of this medication, you should decide what to do based on how long it is until your next dose is due to occur. If you remember that you missed a dose just after the normal time slot, you should take it once you remember. If it is closer to the time of your next dose, however, you should skip the missed one and return to the normal plan. Under no circumstances should you take a double dosage of this medication.


As is the case with many medications, oral or intravenous methyldopa can interact with other drugs once it is inside the human body. These interactions can cause adverse effects, and as a result they are best avoided.

In order to ensure problems do not occur, your physician will need to know details of every drug you are currently taking. This includes over the counter medications as well as prescription ones. That way, they can assess the risk of you taking oral or intravenous methyldopa and alter the configuration of your medicines if necessary.

  • Some drugs can interact in a strong way with oral or intravenous methyldopa. These include labetalol.
  • Other drugs can interact in a medium level way with oral or intravenous methyldopa. These include haloperidol, clonidine and some prenatal multivitamins.
  • Finally, some drugs can interact in only a minor way with oral or intravenous methyldopa. These include a large number of vitamins such as Vitamin B12 (also known as cyanocobalamin), Vitamin B1 (also known as thiamine), Vitamin B6 (also known as pyridoxine), Vitamin D3 (also known as cholecalciferol), Vitamin C (also known as ascorbic acid) and Vitamin D2 (also known as ergocalciferol).

Also included in this final category are Tylenol (or acetaminophen) and Benadryl (or diphenhydramine).

Remember, these lists of interactions are not exhaustive. Your physician is responsible for making the decision about your suitability for taking this drug.


This medication comes with a number of important warnings and precautions which you should familiarise yourself with fully.

Even if you are not sure whether any of these will apply to you, you should still consult the information booklet which comes with the drug in order to find out whether there are any relevant ones. You should retain this booklet for the duration of your treatment in case you need to refer back to it.

It is important to remember that this medication should not be used with the aim of curing high blood pressure. Instead, it should be seen as a method of controlling your hypertension. In some cases, you will be asked by your physician to carry out other methods of controlling your high blood pressure, perhaps simultaneously. These can include lifestyle changes, such as weight management.

Many people who experience high blood pressure do not necessarily know that they are suffering from the problem. As a result, it may be tempting to no longer take your oral or intravenous methyldopa. However, you should remain on this medication for as long as your physician has told you to.

It is possible that you will experience drowsiness as a result of taking this medication. In some cases, this feeling of drowsiness has been known to increase around the time you increase the amount you're taking or when you begin to take it in the first place. For that reason, you should take care not to drive or use machinery until you are fully aware of what effects oral or intravenous methyldopa is having on you.

Taking medical tests or having any surgery done can be problematic while taking this medication. In the case of testing, it can seriously affect your results. For that reason, you should inform whoever is carrying out the test before having it done. In addition, if you find yourself having surgery (including dental work or emergency surgery) you or someone with you should inform the staff that you are currently taking oral or intravenous methyldopa.

If you find that you begin to suffer from a fever while you take this medication, you should speak to your physician immediately. This is because in some cases a fever can be a sign of an adverse reaction to the medication.

This list is not exhaustive, so you should ensure that you read the full list provided in the information booklet which comes with your medication.


For the safety of yourself and those around you, it is important that you follow some rules regarding the storage of this medication.

Firstly, you should ensure that this medication is kept in a location where it cannot be accessed by children and accidentally consumed. This rule applies even if you do not have children living with you at home, as you may forget to move it if children come to visit in the future.

This medication should be kept in a container where it can be closed. This container should then be stored at room temperature and kept out of adverse environmental conditions such as high levels of heat, excessive light and areas of high moisture levels. You should never freeze your oral or intravenous methyldopa.

You should not stop taking this medication before the end of your prescribed dosage period without approval from your physician. However, in the event that you have leftover supplies of oral or intravenous methyldopa which you no longer plan to use, do not keep any leftover medication. You should ensure you dispose of it in an appropriate manner.

This is particularly important for used needles if you take the intravenous route: these should always be disposed of in a hard-to-access location.

If you are unsure how to go about doing this, you should speak to a healthcare professional who can advise you on the best method.


Used to treat high blood pressure, this medication works by relaxing your blood vessels to improve blood flow. It is only available with a prescription from a physician and it is known in the USA as Aldomet. It can be taken as a tablet, as a suspension or as a solution.

There are a number of potential side effects associated with taking this medication, although there is no guarantee you will or will not experience particular ones. One of these side effects, experiencing fever just after commencing your course of this medication, requires you to consult your physician right away. Others, such as pains in your joints, require you to consult your physician as soon as possible. Others, such as headaches, only need a physician's attention if they are causing lots of problems or won't go away.

You should follow the instructions of a physician when taking this medication. Although general dosage information is available, it should never supersede the instructions of your physician. If you miss a dose of this medication, you should decide what to do based on how close in time it is until your next scheduled dosage.

This medication can interact with others once it is inside the human body. As a result, your physician should be made fully aware of all of the drugs you are currently taking, including both over the counter medications and prescription ones. That way, they can make a decision on whether this medication suits your current configuration of medication.

There is a list of warnings associated with this drug which you can find in full in the information booklet which accompanies the medication. You should consult this list in full so that you are aware of what may happen when you take this drug.

This drug requires proper storage in a closed container away from adverse environmental conditions. You should ensure that the drug is stored well out of the reach of children. You should consult a healthcare professional for advice if you are unsure as to how you should dispose of any leftover medication you have in your possession.

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