If you’re managing hyponatremia - low sodium in the blood - you’ve probably heard of Natrise (tolvaptan). It’s one of the few drugs approved specifically to raise sodium levels, especially in cases caused by SIADH, heart failure, or liver cirrhosis. But it’s not the only option. And for many people, it’s not the best fit. Side effects, cost, and monitoring requirements make some patients look for alternatives. So what else is out there? And how do they stack up?
What Natrise (Tolvaptan) Actually Does
Natrise contains tolvaptan, a vasopressin V2 receptor antagonist. That’s a fancy way of saying it blocks the hormone that tells your kidneys to hold onto water. When you have hyponatremia, your body often retains too much fluid, diluting your sodium. Tolvaptan lets that extra water pass out as urine without pulling sodium with it. That’s why it’s so effective at slowly raising sodium levels - usually by 0.5 to 1 mmol/L per hour, which is safe if done right.
It’s approved for adults with:
- SIADH (syndrome of inappropriate antidiuretic hormone secretion)
- Heart failure with low sodium
- Autosomal dominant polycystic kidney disease (ADPKD) - though this use is less common now due to safety concerns
But here’s the catch: Natrise requires strict monitoring. Your doctor will check your sodium levels daily at first. Too fast a rise -over 8 mmol/L in 24 hours - can cause osmotic demyelination, a serious brain injury. That’s why it’s only prescribed in hospitals initially, and often not for long-term use.
Why People Look for Alternatives
Many patients stop Natrise because of side effects. Dry mouth, thirst, and frequent urination are common. Some report headaches, dizziness, or elevated liver enzymes. In rare cases, liver damage has been reported - which is why the FDA requires a black box warning.
Cost is another big factor. A 30-day supply of Natrise can cost over £800 in the UK without insurance. Even with NHS coverage, there may be delays or restrictions. For older adults or those on fixed incomes, this isn’t sustainable.
Then there’s the monitoring burden. Daily blood tests, strict fluid intake rules, and frequent clinic visits make Natrise hard to stick with. Some patients prefer simpler, safer options - even if they’re less powerful.
Fluid Restriction: The First-Line Alternative
Before jumping to drugs, doctors often start with fluid restriction. If your hyponatremia is mild to moderate and caused by SIADH, cutting daily fluid intake to 800-1200 mL can help sodium levels rise naturally. It’s free, has no side effects, and works for about 40% of patients.
It’s not glamorous. You have to count every sip - coffee, soup, fruit, even ice cubes. But for someone with mild symptoms like fatigue or mild confusion, it’s often enough. A 2023 study in The Lancet Diabetes & Endocrinology showed that fluid restriction normalized sodium in 52% of SIADH patients over 14 days, with no adverse events.
It’s not a fix for everyone. If your sodium is below 120 mmol/L or you’re confused, you need faster action. But for many, it’s the smart first step.
Demeclocycline: The Old-School Option
Demeclocycline is an antibiotic that’s been repurposed for hyponatremia since the 1970s. It causes nephrogenic diabetes insipidus - meaning your kidneys stop responding to vasopressin, just like tolvaptan does. But it’s not a targeted drug. It affects multiple systems.
Pros:
- Very cheap - under £20 for a month’s supply
- Oral, once or twice daily
- Works well for chronic SIADH
Cons:
- Slow - takes days to weeks to work
- Can cause sun sensitivity, nausea, or kidney issues
- Not safe for people with liver disease or pregnant women
- May interact with other antibiotics or blood pressure meds
It’s rarely used in the UK now, but some GPs still prescribe it for elderly patients who can’t tolerate Natrise or can’t afford it. It’s not ideal, but it’s a fallback.
Conivaptan: The IV Option
Conivaptan is the injectable cousin of tolvaptan. It blocks both V1a and V2 receptors, making it more potent. But it’s only approved for hospital use - and only for severe hyponatremia with neurological symptoms like seizures or coma.
It works faster than Natrise, often lifting sodium levels in 6-12 hours. But you need an IV line, constant monitoring, and a hospital bed. It’s not for home use. And it’s expensive - about £1,200 per dose.
Most patients who get conivaptan are stabilized and then switched to oral therapy like Natrise or fluid restriction. It’s a bridge, not a long-term solution.
Sodium Supplements: Salt Pills and Oral Solutions
For mild hyponatremia caused by low salt intake - like in elderly people who eat poorly or athletes who overhydrate - sodium supplements can help.
These come as:
- Sodium chloride tablets (e.g., 0.5g or 1g doses)
- Oral sodium solutions (like NaCl 3% drops)
They’re not a cure for SIADH or heart failure. But if your sodium is low because you’re not eating enough salt - maybe you’re on a low-sodium diet for high blood pressure - adding back 1-2 grams per day can make a difference.
One study from the University of Bristol in 2024 found that elderly patients with mild hyponatremia and poor appetite improved sodium levels by 4 mmol/L in 10 days with daily sodium tablets, without needing drugs.
But don’t self-prescribe. Too much sodium too fast can cause high blood pressure or fluid overload. Always work with your doctor.
Loop Diuretics: Sometimes Used, But Risky
Loop diuretics like furosemide (Lasix) are sometimes used in heart failure patients with hyponatremia. They help remove excess fluid, which can indirectly raise sodium.
But here’s the problem: they also flush out sodium. If you’re already low, this can make things worse. They’re only used when fluid overload is the main issue - not when sodium is low due to water retention.
Doctors may combine them with salt supplements or restrict fluids to balance it out. But they’re not a direct alternative to Natrise. More of a supporting player.
Choosing the Right Option for You
There’s no one-size-fits-all. Your best choice depends on:
- How low your sodium is
- What’s causing it (SIADH? Heart failure? Medication side effect?)
- Your age and other health conditions
- Your ability to monitor and follow rules
- What you can afford
Here’s a quick guide:
| Treatment | Speed of Action | Cost (UK) | Monitoring Needed | Best For | Risks |
|---|---|---|---|---|---|
| Natrise (Tolvaptan) | Fast (hours to days) | £800+/month | Daily blood tests, strict fluid limits | SIADH, moderate-severe hyponatremia | Liver damage, overcorrection, thirst |
| Fluid Restriction | Slow (days to weeks) | Free | Self-monitoring fluid intake | Mild SIADH, elderly patients | Dehydration if too strict |
| Demeclocycline | Very slow (weeks) | £15-20/month | Monthly liver tests | Chronic SIADH, low-cost need | Sun sensitivity, kidney stress |
| Sodium Supplements | Gradual (days) | £10-30/month | Weekly sodium checks | Low dietary intake, mild cases | High blood pressure, fluid overload |
| Conivaptan | Very fast (hours) | £1,200+/dose | ICU-level monitoring | Severe neurological symptoms | Overcorrection, IV complications |
What Most Doctors Recommend Today
In the UK, the trend is shifting. The NICE guidelines (2024 update) now say: start with fluid restriction for mild cases. Use Natrise only if that fails - and only if you can commit to monitoring.
For chronic SIADH in older adults, many endocrinologists now prefer demeclocycline or even just careful sodium supplementation - especially if the patient has multiple medications or liver issues.
And for heart failure patients? The focus is on optimizing diuretics and ACE inhibitors first. Sometimes, correcting the heart failure itself fixes the sodium problem.
Natrise isn’t outdated. It’s just not the first choice anymore. It’s a tool - powerful, but with limits.
What to Ask Your Doctor
If you’re on Natrise or considering it, here are five questions to ask:
- What’s causing my low sodium - and is it likely to improve on its own?
- Have we tried fluid restriction first? How much should I drink daily?
- What are the risks of liver damage with Natrise? Will I need monthly blood tests?
- Are there cheaper or safer options for me long-term?
- What happens if I stop Natrise? Will my sodium drop again?
Don’t assume Natrise is the only option. Many patients feel stuck because their doctor didn’t offer alternatives. But there are choices - and the right one depends on your life, not just your lab results.
Final Thoughts
Natrise works. But it’s not magic. It’s a medication with risks, costs, and strict rules. For many people, simpler, safer options - like drinking less water or taking salt pills - work just as well over time.
Hyponatremia isn’t just a number on a blood test. It’s about how you feel: tired, dizzy, confused. The goal isn’t just to fix the number - it’s to help you live better. Sometimes, that means skipping the expensive drug and choosing a quiet, steady approach.
If you’re unsure, ask for a referral to an endocrinologist. They specialize in hormone-related imbalances like this. And don’t be afraid to ask: Is there another way? You deserve options that fit your life - not just your diagnosis.
Can I take Natrise without a hospital stay?
In the UK, Natrise is usually started in hospital for the first few days so doctors can monitor your sodium levels closely. After that, if your levels stabilize and you’re not at risk of overcorrection, you may be allowed to continue at home. But you’ll still need daily blood tests for at least a week and strict fluid limits.
Does Natrise cause weight loss?
Yes - and that’s the point. Natrise makes you urinate more water, so you’ll lose fluid weight, not fat. Many patients lose 1-3 kg in the first week. This isn’t a weight-loss drug. The goal is to correct sodium, not shrink your body. If you’re losing weight rapidly without drinking less, tell your doctor.
Is demeclocycline safe for older adults?
It can be, but with caution. Demeclocycline can cause sunburn, dizziness, and kidney stress - all more common in older people. It’s usually avoided in those over 75 or with kidney disease. But for healthy seniors with chronic SIADH who can’t afford Natrise, it’s still used under close supervision.
Can I drink alcohol while on Natrise?
No. Alcohol increases water retention and can make hyponatremia worse. It also stresses the liver - which is already at risk with Natrise. Even one drink can undo your progress. If you drink regularly, talk to your doctor about quitting or cutting back before starting treatment.
What happens if I miss a dose of Natrise?
If you miss one dose, take it as soon as you remember - unless it’s almost time for your next dose. Don’t double up. Missing doses can cause sodium to drop again, especially if your condition is unstable. If you miss more than two doses in a week, contact your doctor. You may need a blood test to check your levels.
Are there natural ways to raise sodium?
Yes - but only for mild cases. Eating more salty foods (like broth, pickles, or salted nuts) can help if your low sodium is due to poor diet. But if it’s caused by SIADH or heart failure, food alone won’t fix it. Never try to raise sodium with salt supplements without medical advice - too much can be dangerous.
Next Steps
If you’re on Natrise and it’s not working - or if the side effects are too much - don’t stop on your own. Talk to your doctor about switching to fluid restriction, sodium supplements, or demeclocycline. Keep a log of your symptoms, how much you drink, and your weight each day. That data helps your doctor decide what’s next.
Hyponatremia is manageable. But it’s not a one-drug fix. The best outcome comes from matching the treatment to your body, your lifestyle, and your goals - not just the lab report.