The infection was the easy part. A few days of fever and a sore throat, then you tested negative and went back to work. That was the plan, anyway.

Three months later you're standing at the kitchen counter, and your heart is hammering as if you'd just run for a bus. You haven't moved. You only stood up from the couch. Your vision has gone gray at the edges. You hold the counter and wait. When you tell people, they say "you look fine," and the worst part is that you do.

This is one of the quieter outcomes of the last few years. For a meaningful number of people, a viral illness didn't end when the test turned negative. Something in the body's automatic control system stayed shifted. For many of them, that something has a name: postural orthostatic tachycardia syndrome, or POTS.

What POTS actually is (and isn't)

POTS is a disorder of the autonomic nervous system, the part of you that handles things you never think about, like heart rate, blood vessel tone, and digestion. When you stand up, gravity pulls blood toward your legs and gut. In a healthy body, blood vessels tighten within seconds and the heart nudges its rate up slightly to keep blood reaching your brain.

In POTS, that handoff is clumsy. Blood pools, the brain gets less than it wants, and the heart compensates by racing. The clinical definition is a sustained heart rate increase of at least 30 beats per minute within ten minutes of standing (at least 40 for teenagers aged 12 to 19), without a significant drop in blood pressure, along with symptoms that have lasted at least three months.

That last part matters here. The three-month requirement is part of why post-viral POTS gets missed. For the first weeks, everyone assumes you're still recovering. By the time it's clearly not ordinary recovery, you've often been told it's deconditioning, stress, or anxiety.

Why a virus can do this

POTS after infection isn't new. Clinicians were describing onset after viral illness, surgery, pregnancy, or trauma long before COVID-19. Many patients in older studies say their symptoms began after a flu-like illness. What changed is the sheer number of people who suddenly met the pattern at once, and researchers noticed.

The honest scientific answer is that the mechanism isn't settled, and it probably isn't one thing. Several hypotheses are being actively studied:

  • Autoimmunity. Some people with POTS carry autoantibodies that appear to interact with receptors involved in blood vessel and heart rate control. An infection could plausibly trigger the immune system to misdirect itself. This is a leading hypothesis, not a proven cause for everyone.
  • Low or poorly regulated blood volume. Many people with POTS have reduced plasma volume or trouble retaining fluid, which makes pooling worse.
  • Small fiber neuropathy. Damage to tiny nerve fibers that tell blood vessels in the legs and abdomen to constrict may let blood pool. Skin biopsy studies have found this in a subset of patients.
  • Excess norepinephrine signaling. In some subtypes, the body floods itself with adrenaline-like chemicals on standing, which produces the pounding heart, shakiness, and the feeling that your body is panicking when your mind isn't.

It's also worth knowing that not everyone with long COVID has POTS. Long COVID is a broad umbrella, and fatigue, brain fog, and breathlessness can come from other causes. But orthostatic intolerance, meaning symptoms that appear on standing and ease when lying down, is common enough in this population that it deserves to be checked on purpose.

The tell: it follows your posture, not your feelings

The most useful clue for separating POTS from other post-viral problems is the pattern. Ask yourself:

  • Do symptoms ramp up within minutes of standing and ease within minutes of lying down?
  • Is standing still worse than walking?
  • Are mornings, hot showers, big meals, and long lines worse than other times?
  • Do you get a racing pulse, lightheadedness, shakiness, or a strange heavy feeling in your legs without any emotional trigger?

If yes, the problem may be mechanical, not psychological. Anxiety can accompany POTS, understandably, but a pounding heart that reliably follows a change in posture is not the same thing as worry. That distinction is worth holding onto when someone suggests you're just stressed.

How it's actually confirmed

A diagnosis rests on measuring your heart rate and blood pressure lying down and then standing, with readings taken over about ten minutes. That can be done as a formal active stand test in a clinic or, in some cases, a tilt table test. Doctors also typically rule out other things that can mimic POTS, such as anemia, thyroid problems, dehydration, arrhythmias, and medication effects.

A tip that comes up often among clinicians: the test is most informative when you're not freshly rehydrated and propped up. Ask your doctor whether there are instructions about food, fluids, and medications beforehand, and don't change anything on your own before you've asked.

Your next moves

None of these require a diagnosis first. They give you better information and make your next appointment more productive.

  • Run a home stand test this week. Lie down flat for ten minutes. Take your pulse (or use a wearable) and note it. Then stand still, leaning lightly against a wall, and record your pulse at 1, 3, 5, and 10 minutes. Write down any symptoms. Stop and sit or lie down if you feel faint. A rise of 30 or more beats is worth bringing to a doctor, though a home reading is a clue, not a diagnosis.
  • Write a one-page timeline. Note the date of the infection, when you thought you'd recovered, and when the standing-related symptoms began. A clean timeline makes "this started after a virus" concrete instead of vague.
  • Keep a two-week symptom log. For each day, note posture-linked symptoms, sleep, food, fluids, and rough activity. Patterns that you can't see from inside a bad day often show up on paper.
  • Book an appointment and use specific language. Say: "My heart rate rises sharply when I stand, and my symptoms improve when I lie down. I'd like to be evaluated for orthostatic intolerance or POTS." Bring your stand test numbers.
  • Ask before you add anything. Salt, extra fluids, and compression garments are common first steps for POTS, but they aren't right for everyone, particularly if you have high blood pressure or kidney or heart conditions. Check with your clinician before changing your intake.
  • Reduce standing still. While you wait, sit for tasks like chopping vegetables or brushing your teeth, and lie down earlier when symptoms start rather than pushing through them.

The hardest part is the waiting

The strange grief of post-viral illness is that there's no clear moment when it started and no clear sign it's ending. People around you moved on from the pandemic, and you're still negotiating with your own staircase.

Two things are worth remembering. First, what you're feeling has a physical, measurable basis for many people, even when standard bloodwork comes back normal. Second, post-viral POTS is something many people improve with, over months to years, through treatment and pacing, though the timeline varies and no one can promise yours.

What helps most in the meantime is turning a confusing blur into data. A pulse reading, a note on what you were doing, a pattern across days. That is what lets a doctor believe you quickly, and it's what lets you believe yourself on the days you doubt it.

That's the idea behind Stable, a POTS tracker built around exactly this kind of record: standing heart rate, symptoms, triggers, and how a week really went, all in one place you can show a clinician. If you'd rather start with a notebook and a pulse oximeter, that works too. But if you want something that keeps the pattern for you, you can take a look at Stable.