If you have high blood pressure, there is a good chance you have either taken losartan, been offered losartan, or know someone who has. It is one of the most prescribed medications in the United States, with tens of millions of prescriptions filled every year. Here in Bulloch County, I see losartan come across the counter at all four of our Walker Pharmacy locations almost every single day.

Losartan (brand name Cozaar) was first approved by the FDA back in 1995 and was actually the first medication in a class of drugs called angiotensin II receptor blockers, or ARBs. Since then, it has become a workhorse of cardiovascular care. Doctors reach for it to treat high blood pressure in adults and children six and older, to protect the kidneys in patients with type 2 diabetes, and to reduce the risk of stroke in certain patients with high blood pressure and an enlarged heart muscle.

If your provider has just started you on losartan, or you have been taking it for years and have always wondered exactly what it does inside your body, this article is for you. My goal is to give you a plain-spoken, pharmacist-to-neighbor explanation of how losartan works, what to watch for, and how to get the most out of your therapy.

How Losartan Works

Your body makes a hormone called angiotensin II. Think of it as a tiny chemical messenger whose main job is to tighten up your blood vessels and tell your kidneys to hold onto sodium and water. Both of those things raise blood pressure. In a healthy person, this system is helpful — it keeps your pressure from dropping too low when you stand up or lose blood. The trouble is that in people with chronic high blood pressure, this system runs hot, and the constant squeeze on the arteries makes the heart work harder than it should.

Losartan steps in and politely blocks the door. It binds to the receptors (called AT1 receptors) where angiotensin II would normally attach, so the message never gets through. Blood vessels relax, the kidneys release more sodium and water, and over a few weeks blood pressure settles into a healthier range. Because it works further down the chain than older drugs called ACE inhibitors (lisinopril, enalapril, and others), losartan is much less likely to cause that nagging dry cough some people get on those medications.

Common Side Effects and How to Manage Them

Most folks tolerate losartan very well — that is one of the reasons it has stayed so popular for thirty years. When side effects do show up, they are usually mild and tend to fade after the first week or two. Here are the ones we counsel on most often at the pharmacy:

• Dizziness or lightheadedness, especially when standing up quickly. This is most common with the first few doses or after a dose increase. Stand up slowly, sit on the edge of the bed for a moment in the morning, and stay well hydrated.
• Headache. Often improves within a week. Acetaminophen (Tylenol) is generally a safer choice than ibuprofen or naproxen for occasional headaches in people on blood pressure medication — ask us if you are not sure.
• Stuffy nose, sinus congestion, or sore throat. Annoying, but usually temporary. A saline nasal rinse can help.
• Upset stomach, nausea, or diarrhea. Try taking your dose with a small snack and stick to bland foods for a few days.
• Back pain or muscle aches. Usually mild. Let your provider know if it lingers more than a couple of weeks.

There are also a few less common but more serious effects to know about. Losartan can raise potassium levels in the blood, drop blood pressure too low, or affect kidney function — particularly if you become dehydrated from a stomach bug, heavy sweating, or new diuretic use. Call your doctor right away if you notice swelling of your face, lips, or tongue (a rare reaction called angioedema), severe dizziness or fainting, an irregular heartbeat, or you stop making urine the way you normally do.

Things Your Pharmacist Wants You to Know

1. Take it at the same time every day, with or without food. Losartan works best when blood levels stay steady. Pick a cue you will not forget — brushing your teeth, the morning coffee pot, the evening news — and pair it with the dose. Missing the occasional pill will not hurt you, but if you skip several days in a row your blood pressure can climb. Never double up to make up for a missed dose; just take the next one on schedule.

2. Watch out for “salt substitutes” and certain supplements. Many salt-free seasonings sold at the grocery store replace sodium with potassium chloride. Combined with losartan, that can push potassium levels into a dangerous range. The same goes for certain herbal products and some over-the-counter NSAIDs (ibuprofen, naproxen) used for more than a few days. Always run new vitamins, supplements, and even “natural” remedies past your pharmacist before adding them to your routine.

3. Tell us right away if you are pregnant, planning to be, or breastfeeding. ARBs like losartan can cause serious harm to a developing baby, especially in the second and third trimesters. If pregnancy is even on the horizon, your provider needs to switch you to a safer blood-pressure medication well in advance. There is no judgment and no embarrassment — this is the kind of conversation we have all the time.

A Pharmacist’s Perspective

I have been filling losartan prescriptions for as long as I have been a pharmacist, and I will tell you what I tell every patient who picks up a new bottle: blood pressure medication only works if you actually take it. That sounds obvious, but adherence is the single biggest reason controlled hypertension gets out of control. Life happens — vacations, a stomach bug, a refill that slipped your mind — and before you know it a week has gone by without a dose. If that ever happens, do not panic, do not double up, and do not stop on your own. Call us. We can usually get you a same-day refill or a short emergency supply at any of our four locations across Statesboro, Brooklet, and Lyons.

The other thing I encourage every losartan patient to do is keep an eye on the numbers. A simple home blood pressure cuff is one of the best investments you can make in your own health. We carry several reliable models at the pharmacy and we are happy to teach you how to use one correctly. Bring your readings with you to your next doctor visit — those numbers are gold for fine-tuning your treatment plan.

Frequently Asked Questions

Is losartan the same thing as lisinopril?

No, although they are easy to confuse because the names sound similar and both treat high blood pressure. Lisinopril is an ACE inhibitor and losartan is an ARB. They work on the same hormone system but at different points. The most noticeable practical difference for patients is that losartan is much less likely to cause the dry, hacking cough that some people develop on lisinopril.

What time of day should I take losartan?

Either morning or evening is fine — what matters most is consistency. Some patients prefer evening dosing because any first-dose dizziness is less noticeable while you are sleeping. If you take a diuretic (“water pill”) in the morning, you may find evening losartan more comfortable. Talk to your pharmacist about what fits your routine best.

Can I drink alcohol while taking losartan?

Occasional, moderate alcohol use is generally okay for most losartan patients, but alcohol itself lowers blood pressure and can make dizziness worse — especially when combined with the medication. Heavy or binge drinking should be avoided because it raises blood pressure long-term and can damage the liver and kidneys, both of which clear losartan from your body. When in doubt, ask your provider.

How long does it take for losartan to start working?

You may see some blood pressure lowering within the first six hours of your very first dose, but the full effect usually takes three to six weeks of daily use. Do not be discouraged if your numbers do not budge much in the first few days — give it time and keep taking it as prescribed.

What should I do if I miss a dose?

Take it as soon as you remember, unless it is almost time for your next dose. In that case, skip the missed dose and resume your normal schedule. Never take two doses at once to “catch up” — that can cause your blood pressure to drop too low and leave you feeling dizzy or faint.

We Are Here to Help

Have questions about losartan or any of your medications? Stop by Walker Pharmacy in Statesboro, Brooklet, or Lyons, call us at 912-681-3784, or visit walkerpharmacy.com. Need a refill? Request one anytime at walkerpharmacy.com/refills. Ready to switch from a chain pharmacy to a hometown one that knows your name? Transferring your prescriptions takes just seconds at walkerpharmacy.com/transfer-prescriptions.

This article is for informational purposes only and does not constitute medical advice. Always consult your physician or pharmacist before making changes to your medications.

— Jordan Walker, PharmD | Owner, Walker Pharmacy