Losartan (Oral)

By preventing the production of a natural body substance which causes tightening and narrowing of the arteries, losartan helps to relieve high blood pressure and improve circulation.


Losartan belongs to the class of drugs known as angiotensin II receptor blockers, and that means it blocks the production of a substance that naturally causes a constriction of the blood vessels, thereby decreasing blood flow and increasing blood pressure. Since high blood pressure can significantly add to the work that must be done by the heart and all the body's blood vessels, it can cause tremendous stress on them over a long period of time. This in turn, can greatly increase the risk of heart disease, heart attack, and stroke.

Because losartan has the effect of relaxing blood vessels, more blood can flow through them, and the pressure is relieved. This lowers the risk of causing other serious medical problems, especially to the lungs, heart, and kidneys. Patients who have Type II Diabetes are also greatly helped by this medication, since it can help prevent constriction of vessels leading to and from the kidneys, and helps to keep the heart functioning correctly.

This medication comes in the form of a tablet which is to be taken orally, and is only available via prescription from a doctor. It will always be issued with a Patient Information Guide, and this should be read thoroughly by the patient each time a refill of the prescription is obtained, in case something about the medication or its usage has changed since the last time.

Condition Treated

High Blood Pressure

Type Of Medicine

Angiotensin II Receptor Blocker

Side Effects

In addition to the highly beneficial effects that losartan provides for the management of high blood pressure, there is also a possibility that this medication may impart some unwanted side effects to a patient being treated with it. Not all patients will experience any side effects, and some will experience severe side effects. Depending to a large degree on the body chemistry of any specific individual, side effects could be low or high in number, and mild or severe in degree.

If you should experience any of the side effects listed below, you should contact your doctor and discuss which side effects you are feeling, as well as what you consider to be their severity. Severe side effects may require medical treatment, and if you do experience some of these, it is possible that your doctor will either discontinue your usage of losartan, or will recommend that the dosage level be reduced to see what effect it has on your body.

One of the most important side effects to be concerned about with this medication, and most other medications as well, is the potential for an allergic reaction to the medicine. Since an allergic reaction can become life-threatening, you should be alert to the symptoms which identify the condition as an allergic reaction:

  • Hives and/or rashes appearing on the skin surfaces of the body
  • Itchiness all over
  • Tightness in the chest, often accompanied by severe difficulty with breathing
  • Dizziness or lightheadedness, sometimes so severe that it feels like you might pass out
  • Swelling or puffiness in the area around the eyelids, or on the tongue, lips, or throat.

Some of the most commonly experienced side effects by patients being treated with losartan are those listed below:

  • Difficulty breathing with any kind of exertion
  • Unusual bleeding or bruising
  • Shakiness or trembling
  • Slurred speech
  • Abdominal pains or cramping
  • Stomach pains or cramping
  • Pain in the bladder
  • Seizures or convulsions
  • Skin which is pale in appearance
  • Shortness of breath
  • Nightmares or hallucinations
  • Tingling or a sensation of numbness in the feet, lips, or hands
  • Nausea and/or vomiting
  • Cold sweats, chills, or fever
  • Coma
  • Confusion or disorientation
  • Persistent severe headaches
  • Increased frequency of urination
  • Increased urgency of urination
  • Fast or irregular heartbeat
  • Dizziness
  • Feelings of depression
  • Skin which is cool and pale
  • Urine which is cloudy or bloody
  • Anxiety or agitation on a frequent basis
  • Side pain
  • Lower back pain
  • Notable increase in hunger
  • Urination which is painful or causes a burning sensation
  • Uncharacteristic weakness or tiredness
  • Heavy legs
  • Stools that are black and/or tarry
  • Bleeding gums
  • Dark-colored urine
  • Muscle pain or stiffness
  • Persistent coughing
  • Trouble with swallowing
  • Hives and or rashes
  • Itchiness
  • Weakness in the arm or leg on one side of the body, coming on suddenly and severely
  • Awkwardness or unsteadiness
  • Profuse sweating
  • Severe headaches that come on suddenly
  • Discomfort or pains experienced in the jaws, back, neck, or arms
  • Inability to vocalize
  • Fainting spells
  • Large hives which appear on the sex organs, lips, tongue, face, throat, or hands
  • Stools which are light in color
  • Red spots on the skin which have a pinpoint center
  • Chest pains
  • Tightness of the chest or heaviness of the chest
  • Dizziness or lightheadedness when suddenly arising from a sitting position or lying position
  • Temporary blindness or problems with vision
  • Puffiness around the eyelids
  • Skin rashes
  • Yellowish tinge to the skin or around the eyes
  • Swelling around the lips, tongue, or face
  • Persistent dry coughing
  • Congestion in the ears
  • Nasal congestion
  • Runny nose or sneezing
  • Sore throat
  • Belching
  • Difficulty with navigating
  • Heartburn
  • Pain in the joints
  • Indigestion
  • Noticeable lack of strength
  • Increased sensitivity to touch
  • Back pain
  • Sour or acid stomach
  • Pain in the legs or around the knees
  • Swollen joints
  • Difficulty with sleeping
  • Sudden and unexplained weight gain
  • Severe sunburn
  • Discoloration or redness on the skin
  • Frequent passing of gas
  • Loss of appetite
  • Increased sensitivity to sunlight
  • Thinning of hair or hair loss
  • Excess gas in the intestines or in the stomach
  • Sensation of being full or bloated
  • Changes in taste or the outright loss of taste
  • Difficulty with bowel movements
  • Abnormally dry skin
  • Difficulty with hearing or hearing loss
  • Loss of appetite.

Some of the symptoms on the above list may come and go in the first few days after taking losartan, and they will likely eventually subside all on their own without any kind of treatment. This happens as your body adjusts itself to a new medication, and it gets used to the impact of that medication on the various systems of the body.


Remember that losartan will not cure your high blood pressure, but will only help to manage it for as long as you're taking the medication. This means that you should not discontinue taking losartan unless you have first consulted with your doctor, and by the same token, you should not increase your dosage of losartan without first talking to your doctor about it.

The actual dosage recommended for you will be dependent on a number of factors, for instance the exact medical condition you are being treated for, your body's general tolerance to the medication, the frequency of your dosages, the duration of the time frame you have been treated with losartan, and the actual strength of the medicine itself.

The dosages shown below are not meant to be understood as specific patient dosages, especially in your own case, but are instead typical dosages which are often recommended by doctors for the situations they are associated with below.

  • For the treatment of high blood pressure adults should have an initial dosage of 50 mg administered once daily, subject to the doctor's recommended adjustments. Children between the ages of six and 16 will have their dosage determined by age and weight, with an initial dosage usually falling around .7 mg per kilogram of body weight each day. This too will be subject to doctor adjustments, although it is unlikely that a daily dosage will exceed 50 mg. Pediatric patients below the age of six will have a specific dosage calculated by the family doctor, based on circumstances specific to their medical condition.
  • For lowering the risk of stroke in high blood pressure patients, or for the treatment of enlargement of the heart ' a typical adult dosage would be 50 mg administered once daily, pending any adjustments recommended by your doctor. Children's dosage will be calculated by the doctor based on specific medical circumstances.
  • For the treatment of diabetic nephropathy ' adults will be administered 50 mg once daily, subject to the doctor's recommended adjustments as warranted by the effectiveness of the medication. Children's dosages will be determined by the family doctor, and will be based on specific medical circumstances.

If you should miss a dosage of losartan, it is allowable to take the missed dosage as soon as you remember to do so, unless you are coming near the time of your next regularly scheduled dosage. In that case, it's better to skip the missed dosage entirely, and simply wait until the time of the next regularly scheduled dosage. It is never advisable to double up on doses simply to get back on schedule, nor is it advisable to take more medication than is necessary, because you feel that your symptoms are particularly severe on any given day.


There are a number of drug interactions possible when taking losartan, and if at all possible, these interactions should be prevented since neither of the two forms they can take are desirable. The first impact that drug interactions can have is to impart additional side effects to the patient, or to exacerbate any side effects already delivered to the patient. The other possible form that an interaction can take is to diminish the effectiveness of either of the two drugs in question, or both of them.

In order to prevent these undesirable scenarios, both doctor and patient must work together to identify where the potential for interaction exists. As the patient, you should prepare a comprehensive list of all other medications which you are currently taking, including over-the-counter drugs, other prescription medications, vitamins, and herbal supplements, as well as the dosage levels of each one of these.

Your doctor will then review this prepared medication list, and make a determination whether any of those drugs have the potential to interact with losartan. If there is potential, your doctor will probably recommend a reduced dosage level for one of the other medications, or you may be asked to discontinue taking some medication on your list.

You should keep a copy of this list handy so that if you have a need to go to an emergency room for treatment, you can present this to a doctor there and you can then be prescribed a safe program of treatment that does not conflict with your current medication list. You can also use this list if you have a need to go to any healthcare facility where your primary care doctor is not in residence.

Some of the drugs which are most commonly checked by doctors for potential interactions with losartan are the following:

  • Trimethoprim
  • Trandolapril
  • Enalapril
  • Perindopril
  • Benazepril
  • Captopril
  • Ceritinib
  • Clarithromycin
  • Lithium
  • Lisinopril
  • Idelalisib
  • Fosinopril
  • Entacapone
  • Enalaprilat
  • Moexipril
  • Quinapril
  • Nimesulide beta cyclodextrin
  • Niflumic acid
  • Nepafenac
  • Naproxen
  • Aceclofenac
  • Acemetacin
  • Amtolometin guacil
  • Bromfenac
  • Flufenamic acid
  • Fluconazole
  • Floctafenine
  • Feprazone
  • Fepradinol
  • Fenoprofen
  • Nabumetone
  • Morniflumate
  • Meloxicam
  • Meclofenamate
  • Lumiracoxib
  • Loxoprofen
  • Ketorolac
  • Ketoprofen
  • Celecoxib
  • Choline salicylate
  • Clonixin
  • Dexibuprofen
  • Indomethacin
  • Ibuprofen
  • Felbinac
  • Etoricoxib
  • Etodolac
  • Etofenamate
  • Dipyrone
  • Diclofenac
  • Dexketoprofen
  • Diflunisal
  • Lornoxicam
  • Fepradinol
  • Valdecoxib
  • Tolmetin
  • Tenoxicam
  • Sulindac
  • Oxyphenbutazone
  • Piroxicam
  • Proglumetacin
  • Propionic acid
  • Rifampin
  • Proquazone
  • Rofecoxib
  • Salicylate acid
  • Oxaprozin
  • Piketoprofen
  • Propionic acid
  • Salicylate
  • Sodium salicylate
  • Tolfenamic acid
  • Tiaprofenic acid.

In addition to the possibility of interacting with other medications, there is a potential for losartan to impact with existing medical conditions you may have. In order to avoid this possibility, you should consult with your doctor and have a full review of your past medical history, so that he/she is aware of all conditions which you have previously been subject to.

You should especially point out to your doctor any past experience involving the following medical conditions:

  • Electrolyte imbalances these can be made worse by losartan
  • Kidney disease
  • Liver disease'can be worsened because of the slow removal of losartan naturally through body processes
  • Angioedema'an allergic reaction with other types of blood pressure medication such as enalapril, lisinopril, benazepril, Vasotec, Zestril, and Zestoretic
  • Severe congestive heart failure'an trigger kidney problems
  • Diabetic patients ' are at risk if also taking aliskirin
  • Kidney patients ' are at risk if also taking aliskirin
  • Electrolyte imbalances 'specifically low potassium or sodium, or high potassium or sodium, because either of these conditions can be made worse by losartan.


There are a number of precautions to be aware of which all patients taking losartan should take into account. First of all, you should not miss any scheduled appointments with your doctor, because these will be important for evaluating the effectiveness of the medication, and for assessing any side effects which may be imparted to you during treatment. These appointments are good times for you to mention any problems you are experiencing with the medication, and to what degree you are feeling any side effects from it. It may be that your doctor wants to take blood or urine samples during some of these scheduled appointments, to get more detailed information about losartan's effect on your body.

It is possible that losartan can harm an unborn fetus, so women who are pregnant or thinking of becoming pregnant, should discuss the situation thoroughly with the family doctor before becoming pregnant. Generally speaking, it is advisable for you to be using an effective means of birth control while you are being treated with losartan, in order to prevent the possibility of becoming pregnant. If you do become pregnant while taking losartan, you should immediately contact your doctor and discuss the situation.

It's very possible for patients taking losartan to become dizzy or lightheaded immediately after the first dosage of the medicine, particularly if you are also using a diuretic to pass excess water. Make sure that you have a thorough understanding of how this medication affects your body before you attempt to operate any machinery or drive a motor vehicle while being treated with losartan.

Since some patients experience light-headedness or drowsiness after taking losartan, it's very possible that you could become a danger to yourself and other people if the medication affects you in this way. For the same reason, you should not take alcohol or marijuana while being treated with losartan, because it can have the effect of deepening the drowsiness or light-headedness that you might feel as side effects.

Make sure to check with your doctor immediately if you become sick while taking losartan, especially if you experience vomiting which is severe and/or persistent. You should also be aware that there is a potential for severe diarrhea to be experienced by anyone taking this medication, and if this is coupled with another dangerous side effect, profuse sweating, there is a potential for you to become severely dehydrated in a very short period of time. If you notice anything like this in progress, be sure to drink plenty of fluids, and in the meantime contact your doctor about the side effects.

Before you take any kinds of medicines or supplements which contain potassium, you should talk to your doctor about them, because losartan already contains a significant amount of potassium. While you are taking losartan, do not begin taking any new medications or discontinue taking any medications unless you have consulted first with your doctor about it. You should especially avoid taking any over-the-counter medicines for diet control, hay fever, coughs, colds, asthma, or sinus problems, until you have thoroughly discussed the situation with your doctor.


Losartan should be stored at room temperature in a closed container, well away from any extreme conditions of heat, cold, moisture, or direct lighting. Any of these can degrade the quality and effectiveness of the medication. This drug should also be kept out of the reach of pets and small children, and should not be stored in weekly pill reminders, because these usually do not have locking mechanisms that prevent unwanted access.

You should not keep unused medications or expired losartan, but should instead dispose of it according to proper disposal methods given to you by your doctor or pharmacist. If you lack this information, you can consult the FDA website for the safe disposal of medicines.


Losartan is a medication used to help control high blood pressure and is often used in conjunction with other medicines for this purpose. It is available by prescription only, and should only be used under a doctor's supervision. It comes in tablet form and is intended to be taken orally. This medication works by blocking the production of a naturally occurring substance in the body which acts to constrict blood vessels. This allows blood vessels to relax and expand, increasing the flow of blood throughout the body, and lowering the danger of heart problems and kidney problems.