1. What is losartan?
Losartan belongs to a class of drugs called angiotensin II receptor blockers (ARBs). Other drugs in the class include:
Angiotensin II is a hormone that binds to receptors on blood vessels and elsewhere on the body. When it does so, it causes muscles surrounding the blood vessels to contract, which restricts blood flow and increases blood pressure.
ARBs work by blocking angiotensin II from binding to receptors, thus avoiding the contraction that increases blood pressure.
2. What is losartan potassium?
Losartan and losartan potassium are the same thing; the word ‘potassium’ simply refers to its chemical structure and classification.
3. What is losartan-HCTZ?
Losartan-HCTZ is a combination pill that contains losartan and hydrochlorothiazide (HCTZ), a diuretic medicine (diuretics are commonly referred to as water pills).
Diuretics help treat high blood pressure by preventing the reabsorption of electrolytes such as sodium, potassium, chloride, and magnesium, which are subsequently flushed out in your urine along with excess water.
The removal of excess water and electrolytes from blood vessels improves blood flow and lowers your blood pressure.
HCTZ falls under the class of ‘thiazide’ diuretics.
Diuretics are often a first-line treatment for high blood pressure. When diuretics alone are not able to sufficiently lower blood pressure, they will often be combined with another treatment. This is why losartan and HCTZ are available as a combined medication.
4. What is losartan used for?
Losartan is primarily used to treat high blood pressure. Along with other ARBs, it is often used as a first-line treatment. Other first-line treatments include:
- Angiotensin-converting-enzyme (ACE) inhibitors
- Calcium channel blockers
Further treatment options include:
- Renin inhibitors
- Alpha blockers
- Central-acting agents
- Aldosterone antagonists
Your doctor will take into consideration factors such as your age, sex, race, blood pressure level, and other conditions when deciding the most suitable treatment options.
If you do not respond to one type of treatment or have an adverse/allergic reaction, your doctor may try a different medication or a combination of two drugs. For example, losartan and a diuretic, such as HCTZ, may be more effective than either medication is when used alone.
However, some types of drugs are not routinely used in combination, such as ARBs and ACE inhibitors.
Treatment for hypertension will usually include recommendations for healthy lifestyle changes, such as an improved diet or exercise (within one’s capabilities).
5. What are the most common side effects of losartan?
The most common side effects of losartan are:
- Dizziness or having a spinning sensation (vertigo)
- Dry cough
- Feeling sick
- Sickness and diarrhea
- Pain in joints and muscles
These side effects will often go away after a few days, although can last a couple of weeks. If they don’t subside or are severe, you should speak to your doctor.
Serious side effects of losartan are rare. You should contact your doctor immediately if you experience any of the following:
- Yellow skin or the whites of your eyes turning yellow (this can be a sign of liver problems)
- Severe stomach pain
- Chest pain, shortness of breath, or rapid or erratic heartbeat
- Pale skin
- Burning when you urinate
- Feeling very faint or dizzy
- Swelling in your hands, feet, or ankles
- Unexplained weight gain
Serious allergic reactions to losartan are rare. If you do experience signs of a serious allergic reaction, seek medical attention immediately. Symptoms include:
- Swelling of your face, lips, tongue, or throat
- A skin rash that may include itchy, red, swollen, blistering, or peeling skin
- Tightness in your chest or throat
- Wheezing or trouble breathing
Although this covers the majority of known side effects caused by losartan, check the information leaflet for an extensive list.
6. How long does it take for losartan to work?
Losartan starts working almost immediately, generally within around 6 hours of your first dose. It takes 3 to 6 weeks for losartan to take full effect.
Because high blood pressure is often ‘invisible’ and may not have symptoms, you may not feel any difference when you take losartan. That does not mean it is not working. You should continue taking it as prescribed unless told otherwise by your doctor.
7. What is the difference between losartan and valsartan?
Although both losartan and valsartan are ARBs, they interact with your body slightly differently and have different characteristics. Likewise, the other drugs in the class (azilsartan, candesartan, eprosartan, irbesartan, olmesartan, and telmisartan) each differ from one another.
Your doctor will likely take factors such as your blood pressure level, the risk of cardiovascular events (such as stroke or heart attack), and other existing conditions into consideration when deciding which specific ARB is most suitable.
For example, there is recent evidence to suggest losartan is one of the preferred ARBs for reducing the risk of stroke and for patients who also live with diabetic nephropathy (a kidney-related complication of diabetes).
Valsartan, on the other hand, may be preferred for people who have asymptomatic left ventricular systolic dysfunction (ALVSD) following a heart attack.
Aside from other conditions you live with, your doctor may take the half-life of each ARB into consideration. Half-life refers to the amount of time it takes for 50% of the drug to be eliminated from the body. With each half-life, the amount of drug reduces by a further 50%.
Losartan has a shorter half-life (about 2 hours) than valsartan (about 6 hours).
Therefore, losartan will roughly reduce in the following way:
- 2 hours: 50% remains in the body
- 4 hours: 25% remains in the body
- 6 hours: 12.5% remains in the body
- 8 hours: 6.25% remains in the body
It would take around 24 hours, rather than 8 hours, for valsartan to be reduced to 6.25%. Valsartan may, therefore, be more effective at providing 24-hour coverage from a single dose.
Your doctor will likely consider other conditions you live with and the half-life of different ARBs when deciding which is most suitable for you. If you have any concerns about your treatment, you should always discuss them with your doctor.
8. How long does losartan stay in your system?
Given the half-life of losartan, less than 0.1% is still in your system after 24 hours.
However, around 14% of losartan is converted into an active metabolite (E3174). An active metabolite is a chemical left after your body processes a drug. Active metabolites often have a similar therapeutic effect as the original drug but in a less potent form.
For losartan, the active metabolite is actually 10 to 40 times more potent. What’s more, the half-life of E3174 is 3 to 9 hours, so its effect lasts longer. This may help explain the positive results of losartan compared to drugs that have a longer half-life.
It can take 24 to 48 hours for the active metabolite of losartan to effectively leave your body.
9. What is the correct dosage of losartan?
Losartan generally comes in 25 mg, 50 mg, or 100 mg tablets.
A normal starting dose for adults with hypertension is 50 mg once per day, although this may be reduced if combined with a diuretic.
For children between 6 and 18 years old with hypertension, the dosage may be calculated by weight (often 0.7 mg/kg) and will not usually exceed 50 mg per day.
Dosage rarely exceeds 100 mg per day. Rather, other medications, such as HCTZ, may be used in combination with losartan if required.
If you are living with other conditions, they will usually be taken into consideration when your doctor is deciding on the correct dosage.
For example, people living with heart failure may receive a starting dosage of 12.5 mg once per day, which is gradually increased as required.
Your doctor will take your blood pressure levels, age, other conditions, and any other mitigating factors into account when deciding the correct dosage.
10. Should I take losartan in the morning or at night?
It is widely agreed that taking losartan at the same time each day is more important than the actual time of day. There is no conclusive evidence that taking losartan either in the morning or in the evening leads to better or worse results.
However, it could be necessary to schedule when you take losartan around when you take other medications or supplements, to avoid interactions.
Otherwise, it may simply be a case of choosing a time that allows you to achieve consistency.
These topics should be discussed with your doctor, together with whom you can figure out the most suitable time to take losartan.
11. Is losartan safe during pregnancy or when breastfeeding?
No. Losartan, like other ARBs, poses serious risks to a developing baby and can cause birth defects or even a miscarriage. The risks are heightened in the second and third trimesters of pregnancy.
If you are planning on having a baby, speak to your doctor about your options before trying to conceive.
If you think you may be pregnant, speak to your doctor immediately. The risks posed by losartan are present early in a baby’s development, so it is important to find a safe alternative as soon as possible.
It is not known whether losartan passes into breast milk. As such, drugs with a more defined safety profile are usually recommended for women who are breastfeeding.
12. How can I wean myself off of losartan?
Never stop taking losartan without first speaking to your doctor, even if you are feeling better.
Losartan, like other medications that lower blood pressure, is usually required for life, even if it has successfully lowered your blood pressure. Continued use will help keep your blood pressure under control and may help mitigate the risk of a stroke or heart attack.
This is particularly true if the primary underlying causes of your high blood pressure are non-modifiable, such as age, genetics, or another chronic illness.
However, there are some circumstances when stopping treatment may be appropriate, if the primary underlying causes of your high blood pressure are modifiable, such as a high-salt diet, lack of exercise, and smoking. If you have successfully made lifestyle changes that tackle these causes, stopping your treatment may be suitable.
If this is the case, you must discuss it with your doctor. Together you can discuss the best course action, be it continuing your treatment, reducing your dosage, switching to a different medication (such as a diuretic), or stopping your treatment.
13. What foods should I avoid when taking losartan?
Grapefruit and grapefruit juice may reduce your ability to absorb losartan and therefore be avoided.
Losartan and other ARBs tend to increase potassium levels in your bloodstream, which can increase your risk of developing a weak or an irregular heartbeat. Foods high in potassium should, therefore, be limited, such as:
- Bananas, oranges, cantaloupe, honeydew, apricots, raisins, and dates
- Dried fruits
- Potatoes and sweet potatoes
Be aware of salt substitutes, as they often replace sodium with potassium.
You should discuss your consumption of potassium-rich foods, salt substitutes, and potassium supplements with your doctor.
14. Can I take painkillers with losartan?
Some painkillers may reduce losartan’s effectiveness at reducing blood pressure and should not be taken together. This includes non-steroidal anti-inflammatory drugs (NSAIDs) such as:
NSAIDs may also increase your risk of kidney problems when taken together with losartan. You should not take them together unless told to by your doctor.
Paracetamol (acetaminophen) is considered safe to use with losartan.
If you have any questions or concerns about taking painkillers with losartan, you should discuss them with your doctor.
15. Can I drink alcohol while taking losartan?
Although alcohol does not interact with losartan directly, it is recommended that you avoid alcohol for at least a few days when you start taking losartan or when your dose is increased.
Some of the side effects of losartan, such as dizziness, are caused by the blood pressure-lowering effect of the drug. Alcohol also lowers your blood pressure, so the combination can exacerbate the symptoms.
If you live with other conditions, such as heart failure, it is important to discuss your alcohol consumption with your doctor and follow the advice you are given.
16. Should I be concerned about losartan being recalled?
You may have read about batches of losartan and other ARBs being recalled since July 2018, due to being contaminated by chemicals considered to be probable human carcinogens. A carcinogen is a substance capable of causing cancer.
Daunting though that sounds, an FDA laboratory analysis came to the following conclusion:
“FDA previously estimated that if 8,000 people took the highest valsartan dose (320 mg) containing NDMA from the recalled batches daily for four years, there may be one additional case of cancer over the lifetimes of the 8,000 people. That estimate was based on the highest daily dose, however many people may have taken lower doses, and therefore their risks would theoretically be less. FDA expects the actual cancer risk to most consumers to be lower than our estimate.”
The European Medicines Agency also found the risk to be low.
If you are taking losartan, it is therefore important to continue taking your medication as normal. The risks posed by suddenly stopping your medication significantly outweigh the risks posed by the contamination.
If you are in the USA, you can keep track of the latest updates via the FDA website, while a complete list of losartan products being recalled can be found here.
If you are outside the USA, you can check the website of your national regulatory body.
If you are taking losartan that is being recalled, continue taking your medications and speak to your doctor or pharmacist about switching to an alternative treatment.
The content on this page is provided for informational purposes only. If you have any questions or concerns about your treatment, you should talk to your doctor, pharmacist, or healthcare professional. This is particularly important if you are taking multiple medications or have any existing medical conditions.
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