What tadalafil does at 5 mg

Last week I was on a call with a client who leaves for an enormous mountain climb next month. He's one of the most dialed-in athletes I work with, his labs came back about as clean as I've ever seen, and I told him not to change a single thing before he goes.

Then he asked what I'd want to try when he gets back. My answer wasn't a peptide. It was 5 mg of tadalafil.

If that name doesn't ring a bell, the brand name will. It's Cialis.

Most people think of it as a "men over sixty" medication, and I'm suggesting it to a fit man in his forties for his legs and his heart.

I'd suggest it to plenty of women too, and I can already hear the response. "Isn't that a men's drug?"

So let me walk you through what it does, what the research actually says, where the men's and women's stories split, and whether it belongs in your plan.

What it actually is

Tadalafil belongs to a family of drugs called PDE5 inhibitors. Sildenafil, the original Viagra, is the famous one. Tadalafil is the one that lasts.

Sildenafil is in and out of your system in about four hours. Tadalafil stays for a day and a half, which is why doctors began prescribing it at a tiny daily dose, 2.5 to 5 mg, instead of 20 mg on demand. At that dose it stops being an event.

It's FDA-approved for erectile dysfunction, enlarged prostate symptoms, and pulmonary hypertension. So everything else in this article is off-label, but becoming more common reasons doctors are prescribing it.

How it works

Every blood vessel in your body is lined with a single layer of cells called the endothelium.

Laid flat, your endothelium would cover about an acre, a little smaller than a football field!

When that lining is healthy, it releases nitric oxide, which signals the muscle in the vessel wall to relax so more blood gets through. Inside the cell, a molecule called cGMP carries that signal. PDE5 is the enzyme that breaks cGMP down and closes the vessel back up.

Tadalafil blocks PDE5, so the "open" signal lasts longer.

Why does a drug built for one small organ keep turning up in heart, brain, and muscle research? It works on every artery you have.

Nitric oxide production drops steadily after forty in both sexes, so cold hands, slower recovery, rising blood pressure, and weaker erections are one problem showing up in different places.

What the evidence actually shows

The best study is a 2024 analysis of about 29,000 American men with erectile dysfunction. The men who filled a tadalafil prescription had 19 percent fewer heart attacks, strokes, and cardiac procedures over roughly three years than the men who took nothing.

Their overall death rate was 44 percent lower. The men who took the most had the best numbers.

That's a real signal. It's also an observational study.

Men who fill prescriptions tend to be men who see doctors, so some of the benefit may have come from having more sex rather than from the pill. The researchers said so themselves. A pooled analysis of over a million people found the same direction, but 99.4 percent of them were men.

So what does that mean if you're a woman? You just read about a study that doesn't include you.

The Alzheimer's data points the same direction, but it's early, most of it comes from sildenafil, and the users were younger and healthier to start.

What it does for performance

At altitude, the evidence is solid, because thin air constricts the blood vessels in your lungs, PDE5 inhibitors open them back up, and that's why sildenafil improved exercise capacity at Everest base camp in a randomized trial and why tadalafil is used to prevent high-altitude pulmonary edema.

At sea level, one tadalafil trial in athletes found nothing. Fourteen trained men took 20 mg or placebo before a maximal cycling test, and their VO2max, aerobic threshold, and anaerobic threshold didn't move.

So why am I still interested? Because a max test measures one thing, while what I care about for him is blood flow to working muscle, recovery between sessions, and whether his blood pressure creeps up as training volume climbs.

That's a hypothesis, so I told him to test it during a training block at home where a miss costs nothing.

Where the women's story splits

Women have PDE5 in the same places men do, including the clitoris and the vaginal wall, plus the same endothelium everywhere else. So the mechanism is identical. The evidence is not.

The best trial in women wasn't even tadalafil. It was sildenafil, given to 98 premenopausal women whose antidepressants had shut down their arousal and orgasm. Over eight weeks, the women on the drug improved on arousal, lubrication, and orgasm while their depression stayed in remission.

Here's the detail that matters most. The women who responded, on drug or placebo, had higher free testosterone and higher thyroid hormone than the women who didn't.

In other words, the blood flow drug only worked when the hormones underneath it were in place. A 2024 review in the New England Journal went further and found no benefit at all in healthy women with arousal problems.

Neither drug is approved for women. Nobody has studied what either one does for a woman's heart.

That lines up with what I see, because when a woman in her forties tells me "it's just not there anymore," the first question is never blood flow. It's estrogen, testosterone, progesterone, sleep, and whether her nervous system ever gets a break.

Tadalafil doesn't touch desire at all. Desire comes from the brain, so if that's the missing piece, a peptide like PT-141 is the tool instead of this one.

Where it can help a woman is the last step, once hormones are addressed, sleep is repaired, and arousal is still slow to arrive. That's a blood flow problem. This is a blood flow medication.

The short version for men

A daily 2.5 to 5 mg dose means you're never timing anything. If your prostate has started getting in the way, it usually improves urinary flow at the same time.

Morning erections are the earliest warning light you have for your arteries. When they fade, the same thing is happening in vessels you can't see, usually two to five years before a cardiologist finds it.

Tadalafil can restore the erection without fixing the artery. Use it, and treat the warning as a warning.

There's one other caveat here...if men's sleep is terrible, their erections usually will be, too. So before addressing testosterone or tadalafil, make sure sleep is optimal. Otherwise, nothing else works very well.

Who should not take it

Anyone on nitrates for chest pain should never take it, because the combination drops blood pressure hard enough to be dangerous. That's an absolute rule. Anyone on riociguat for pulmonary hypertension is in the same category.

If you take an alpha-blocker or blood pressure medication, start low and check your pressure for two weeks. A heart attack in the past three months, a stroke in the past six, or severe liver or kidney disease means this is a conversation with your cardiologist first.

Side effects are mild and mostly early.

Headache, flushing, and a stuffy nose are the common ones, while back pain and muscle aches are specific to tadalafil and usually fade within a few weeks.

Sudden vision or hearing changes are rare and mean you stop and call your doctor the same day.

Where it belongs in your plan

This is a top layer. It's not the foundation.

Sleep comes first, since for men it's the biggest single driver of testosterone. For women, it's also a huge factor in their hormones, stress levels, and their desire.

Then protein at every meal and strength training, because muscle is where most of your blood flow goes.

Then hormones, checked and corrected, because a blood flow drug on top of low estrogen or low testosterone is a car with a great engine and no fuel.

Once those are in place, a daily 2.5 to 5 mg dose is a reasonable experiment for a man in his forties or older, or a woman who has done the hormone work first. Give it four weeks. Check your blood pressure before and after.

And if you have something big coming up next month, whether it's a climb, a race, or a wedding, don't start it now. I've watched people go from feeling good to breaking something because a new thing made sense on paper.

If you know somebody who thinks this is a men's drug, or a sixty-year-old's drug, send them this.

Two next steps, depending on where you are.

If you're not sure whether a blood flow drug belongs in your plan, or what needs to be in place before it does, that's exactly the kind of question I work through in a consultation. We'll look at your labs, your sleep, your hormones, and your training, and decide together what the next layer should be.

If it's appropriate, you can get the Tadalafil through your doctor or through a compounding pharmacy. 

And if sleep is the layer you haven't fixed yet, that's where I'd start before any of this, because for men it's the biggest driver of testosterone there is. Sermorelin is the peptide I use most for deep sleep and recovery, and you can get it through EllieMD, the telehealth partner I use with my own clients.

And in case you were wondering, yes, I've been using it, too. Outside of the "traditional" benefits you'd expect, I've noticed a substantial difference in vascularity throughout the day, muscle pump during exercise, and a noticeable difference in stamina, even with outdoor work like shoveling muck out of our pond. So, I'm not just writing about this. I use it myself.