Still Tired After a Virus

The distinguishing feature is a disproportionate crash that follows exertion with a delay — typically a day or two later, lasting days, and triggered by less than it should be. Physical effort does it; so does cognitive effort, and so does a demanding social or emotional day. Clinicians call it post-exertional malaise.

It matters more than any other single detail, for a practical reason. Standard advice for fatigue is to build activity back steadily, and for most kinds of tiredness that is right. Where post-exertional malaise is present it is not: national guidance has moved away from recommending structured, incremental exercise programs as a treatment for this illness, in favor of staying within the limits of what your energy currently allows — often described as pacing, or working inside your energy envelope.

Which means the answer to "should I push through" is genuinely different here than almost everywhere else on this site, and getting the distinction wrong costs people weeks. If a day at the gym reliably buys you two days on the sofa, say exactly that in the intake.

Nearly everything about mechanism.

Several hypotheses are under active investigation — persistent immune activation, autonomic nervous system dysfunction, fragments of virus lingering in tissue, changes in small blood vessels and clotting, disturbed energy metabolism in muscle and immune cells. Some have supporting findings. None has produced a diagnostic test in routine use, and none has produced a treatment with established benefit.

That absence is the important part, because it is what the market fills. There is no approved therapy for post-viral fatigue, no supplement shown to resolve it, and no infusion that has been demonstrated to. Where a clinic sells certainty here, the certainty is the product. If you have read about NAD+ specifically, the trials that tried it are set out at NAD+ and post-viral fatigue — including what they could not show.

This is the section worth reading twice, because it is where people in this age group get sold something.

Fatigue after a virus lands on someone who is already in their late forties, fifties or sixties. A testosterone result sits low. A thyroid panel looks slightly off. A cortisol result is not where someone expected. The story assembles itself: the virus disrupted your hormones, so restore them and the energy returns.

Three problems with it.

Illness moves these markers on its own. Acute and prolonged illness suppresses hormonal axes as a normal adaptive response — thyroid readings shift during significant illness in a recognized pattern, and testosterone falls transiently with systemic illness in men. A result drawn during or shortly after illness frequently describes the illness rather than a separate condition, and it often drifts back on its own. Treating that shadow treats nothing.

Correcting a marker does not treat the syndrome. Even where a genuine hormonal deficiency coexists and warrants treatment on its own merits, nothing establishes that doing so resolves post-viral fatigue. Two things can both be true and still not be cause and effect.

The symptom pictures do not match. The defining feature here is the delayed crash after exertion. That is not a feature of low testosterone or an underactive thyroid, and no hormone story explains it.

None of which means the hormonal markers should be skipped. In this age group they belong on the panel exactly as they do for anyone else, read together with everything else and against your own history — see low testosterone and menopause for what those pictures genuinely look like. The point is narrower and firmer: they are not the explanation for this, and they should never be the first and only thing measured.

Post-viral fatigue is identified partly by excluding other things, which means the ordinary workup matters more here, not less. Thyroid function, iron stores, B12 and folate, a blood count, a metabolic panel, glucose control and inflammatory markers are all worth having — both to find a treatable cause hiding behind the assumption, and to establish what is normal for you now. What a baseline panel covers · How to read blood work.

Two additions specific to this situation. Tell the clinician about lightheadedness, a racing heart or feeling faint on standing — orthostatic symptoms are common after infection, they are assessed in person rather than by panel, and they change the advice. And re-read the red flags, because a post-viral label is exactly the kind of explanation that can absorb a symptom that needed investigating in its own right.

We can run and interpret the workup that excludes the measurable causes, screen for sleep-disordered breathing and refer, review the medications contributing to it, and be straight with you about what the evidence does and does not support.

We cannot diagnose ME/CFS or a post-COVID condition. Those are clinical diagnoses requiring in-person assessment and the exclusion of other causes, and they belong with a clinician who can examine you — ideally one working in a service set up for it. We will say so rather than treating around it. How assessment works · Our clinicians.