Generic name: Losartan

Brand name: Cozaar, Hyzaar (containing Hydrochlorothiazide and Losartan)

Losartan is classified as an Angiotensin II Receptor Antagonist medication. Also known as ARBs (Angiotensin Receptor Blockers), these medications are mostly used to treat high blood pressure, but have other uses as well, such as the treatment of congestive heart failure–a condition characterized by a lack of efficient blood flow from the heart to other parts of the body. Other ARBs include Micardis (Telmisartan), Avapro (Irbesartan), or Diovan (Valsartan).

The specific function of Angiotensin Receptor Blockers is to negate the actions of certain substances in the body which cause the blood vessels to tighten. This enables the heart to pump more efficiently and the blood to flow more smoothly throughout the body.

Clinical trials of over 60,000 patients have shown that there is a very small percentage increase in the number of people who have cancer and are taking ARBs as compared to those who have cancer and are not taking ARBs. However, the FDA has yet to conclude officially that ARBs actually cause an increased risk of cancer.


Initial Dose: usually starts at 25mg, taken orally in tablet form once or twice a day.
Maintenance Dose: usually 50 to 100 mg taken orally in tablet form once or twice a day.

It is normal for doctors to prescribe this medication at a low dose and gradually increase the dosage if necessary. Taking Losartan with food is not required. A drop in blood pressure should be imminent after the first dosage; however, it isn’t uncommon for patients to not feel the full benefits of the drug until about 3 to 6 weeks into the treatment.

It is important to remember that Losartan does not cure high blood pressure, it merely controls it. A patient should never stop taking this medication without talking to the doctor first.

Precautions and Adverse Effects

As with all medications, there are necessary precautions to take and some adverse side effects.

Precautions: The patient’s doctor should be consulted about allergic reactions that the patient may experience due to the ingredients in the drug. The doctor should also be informed of any other medications that the patient is currently taking. Some medications in particular could have adverse effects when combined with Losartan. These include but are not limited to NSAIDs, diuretics, Rifampin, Lithium, or Flucanazole. Also, the patient should tell the doctor about any history of heart failure, or diseases of the liver or kidney.

Anybody taking an ARB should be informed before-hand that they cause dizziness, lightheadedness or fainting upon standing up from a sitting or lying down position.

Forgetting a dose: If a daily dose is missed, it is recommended that the patient either take it as soon as possible, or if the next dose is imminent to skip the missed dose altogether. Patients should never double their dose in order to compensate for a missed one.

Side Effects

The patient’s doctor should be notified if any of these conditions are severe or long-lasting.

  • Leg, knee or back pain
  • Diarrhea
  • Lessened sensitivity to touch
  • Muscle cramping
  • Dizziness
  • Heartburn
  • Stuffy nose

Losartan can cause serious adverse effects in certain patients. If any of the following symptoms occur, a doctor should be notified immediately:

  • Swelling of the face, mouth, or appendages
  • Difficulty swallowing/breathing and hoarseness
  • Chest pain

In case of emergency/overdose:

In case of overdose, the poison control center should be called right away (1-800-222-1222). If the person has collapsed or stopped breathing, emergency medical services (911) should be contacted instead.
Symptoms of an overdose of Losartan include:

  • Dizziness
  • Fainting
  • Unusually high heart-rate/pounding heartbeat

18 Responses to Losartan

  1. Nelly Conant says:

    Just curious…I have been taking 200 mg of Losartan for over a year now. I have been in and out of the hostpital for various reasons, from thinking I was having another heart attack, running fevers with infections,running fever and not knowing why, also had pneumonia…My last trip to the hospital, they stopped the 200mg and wrote a script for 100mg….We found out that you are not suppose take more then 100 mg….
    My husband and I have tracked back to see who started me on the 200mg…my first heart doctor we have traced it to…my second heart doctor never noticed I was taking to much of the losartan…. neither did my primary notice….it took this last trip and stay in the hospital that it came up about the amount of Losartan. My primary said it should be out of my system in a couple of weeks…I am still having issues…I’ve had all the side affects…My husband has had to call the ambulance several occassions, the last two, I lost all control of my legs and arms…Can you tell me more about what happens if you over dose for a little over a year ! Thank You

    • shayla says:

      Hi.Jjust found this website and my dad also has been taking 200 mg of losartan but only for a week or so. He is currently hospitalized and is experiencing serious delirium. I noticed that you stated you have experienced all the side effects so has delirium been one of them?

      • 39sdfvnczv9043bb54 says:

        That’s not one of the listed side effects. I would definitely talk to your doctor about that. I hope it passes.

        • Waldo says:

          See Mayo Clinics Drug and Supplement site. One of this drugs “more common” side effects are anxiety, depression, nightmares. It cause extreme anxiety in me (no folks, no prior history of any mental issues ) I was on 50 x2 daily. It takes a few days for your blood level to fall so, hang on

  2. 39sdfvnczv9043bb54 says:

    Your pharmacist should be able to help you. So should your primary doctor. Go see your pharmacist tomorrow and call your doctor. Take care.

    • Nelly Conant says:

      Thank You….My primary has changed me over to Bystolic, which I have a low tolerance to and zombie like feeling, don’t want to do anything…
      The Lorsatan they over dosed me on that…You cannot take over 100mg…they had me taking 200mg for over a year ! I should have been more aware…but I trusted the doctor and pharmacist !
      All I can say now is be more aware of the meds the doctors and check it out before you take the med prescribed !
      Thank you for your reply, Nelly

  3. Marilyn Thomas says:

    When I first started taking Losartan, I thought it was a horrible medicine. And I was only taking 50mg! I was dizzy, lightheaded and just couldn’t concentrate. My energy level was really low, too. But I stuck with it, and after a couple of weeks I felt better. Now I don’t notice any side effects.

    One thing that might help, even if your doctor doesn’t lower your dose, is to take it at night. That helped me a lot because you don’t notice dizziness when you’re lying down. But you are taking a really high dose and I hope they can lower it for you.


    • Nelly Conant says:

      Hi, When I first started Losartan it was a low doesage…Then somewhere along the line I was given the 200mg, which was way to much and every side affect I was having and I am still experiencing side affects….We traced it back through our pharmacist that my first heart doctor had prescribed it…so now we are not sure what we will do….at this point…the longer I took the 200mg dose, I was having really bad side affects….My husband the last two times he called 911 I was not able to walk or have any control of my hands…
      Please teach yourself about the meds your doctor puts you on…it can be so scarey ! Thank You, Nelly

  4. troy harrison says:

    I have been taking 100 mg twice daily of Losartan – no side effect. Higher dosage has done much better job of controlling my BP.

    • dee says:

      Troy, was 100 mg not doing any good? I am on 100mg Losartan once a day and 50mg of Carvedilol twice a day but my BP remains high. I have been wondering about increasing the Losartan to twice a day.

  5. Janet says:

    I believe that Losartan caused my mother to go into a coma and die. She had all the symptoms of an over dose, but the physician neglected to follow up on her blood tests, which proved that she had a dangerously high level of Losartan (cozar) in her blood. I think that until they do some more clinical trials on older adults, that FDA should pull this drug from the market. I will NEVER take this medication, it is not safe.

  6. Candus says:

    Hi Nelly,
    My husband has been on losartan 100 mg/ once per day. It has improved his bp significantly. Over the course of the last 6 months he has been exercising 4-5 days per week and has lost 60 pounds. He was 356 when he started and is now 295 roughly. Recently he has started having dizzy spells and lightheadness upon standing only. We contacted the doctor, concerned that his meds may be too much now with the significant weight loss. The dizzy spells continue despite the rx being changed to
    50mg /d and continue to get worse as his weight goes down. Thoughts???

    • Lisa says:

      When I lost a significant amount of weight they had to lower my dosage as well because I was experiencing the dizziiness. I originally was taking Losartan/HCTZ 100/12.5mg and they lowered it to Losartan 50mg with no HCTZ. Have your doctor check the dosage again.

  7. .steve says:

    I have taken Losartan for the last 3 years plus. I was at 147/94. I retired a year ago
    and took my physical and my blood pressure is now 120/82. I would like to get off Losartan now. I wake up in the middle of the night with my throat very dry. What do you think ?

    • 39sdfvnczv9043bb54 says:

      Sound like your blood pressure is going in the right direction. That’s great! I sometimes wake up with a very dry throat, but I think it’s probably because I was sleeping with my mouth open. I would ask your pharmacist. If they don’t know, check with your doctor.

  8. Trisha williams says:

    Will missed doses be harmful?(of Losartan?

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