Sudden hair loss can be alarming—especially when it seems to show up over a week or two, such as a noticeable increase in hair in a brush or shower drain. In this video, Dr. Patrick Nemechek focuses on sudden-onset shedding rather than long-term thinning patterns like male pattern baldness.
He outlines a practical way to think through common contributors. In his clinical interpretation, many cases come down to a few broad buckets: basic medical issues that should be screened for, intense stress (often described as telogen effluvium), and a rise in systemic inflammation—something he says he has seen frequently after COVID, including after asymptomatic infection.
Medical disclaimer: This article summarizes a clinician’s discussion from a video and is for education only. Sudden hair loss can have multiple causes. Work with your licensed healthcare professional for diagnosis, testing, and individualized care.
First step: don’t skip basic labs
Before assuming the cause is inflammatory or digestive, Dr. Nemechek advises starting with a primary care visit and basic laboratory testing. Specifically, he recommends checking:
- Thyroid function (“make sure your thyroid’s okay”)
- Iron levels
- Other basic labs as directed by your clinician
His point is straightforward: these issues are important not to miss, particularly when the onset is sudden and the shedding is clearly above a person’s baseline.
Intense stress and telogen effluvium
Another common cause Dr. Nemechek highlights is intense stress, which he refers to as telogen effluvium. In this scenario, the hair loss may seem abrupt and significant, but he describes reassuring news: as intense stress levels decline, hair can come back.
In other words, within the framework discussed in the video, stress-related sudden shedding is often reversible—though the key is identifying and addressing the stressor(s) rather than assuming the hair loss is permanent.
Inflammation as a driver of sudden shedding—especially after COVID
Dr. Nemechek then turns to what he calls a very common contributor: a sudden bump in inflammation. He contrasts short-lived inflammatory illnesses (he uses influenza as an example) with a pattern he says he has observed frequently after COVID.
In his explanation, if someone gets an acute inflammatory illness and the inflammation resolves, hair growth may resume and the person may not even notice much hair loss. The concern, as he describes it, is chronic or prolonged inflammation, which he suggests may occur as a “long COVID effect” and may be associated with persistent post-infectious changes.
Notably, he says this persistent inflammation can happen even when the initial COVID infection was asymptomatic. In his clinical observation, a person may feel fine during infection, believe they recovered, and then develop intense hair shedding afterward.
Digestive symptoms, SIBO, and “leaky gut” in Dr. Nemechek’s framework
In the video, Dr. Nemechek describes a clinical case where post-COVID hair loss occurred alongside new gastrointestinal symptoms “suggestive of SIBO or bacterial overgrowth.” In his framework, chronic inflammation may be driven by issues such as:
- Bacterial overgrowth (SIBO)
- Leaky gut
- A COVID-related form of leaky gut, which he describes as different from what is found with SIBO
He emphasizes that COVID can cause “a very different form of leaky gut” than SIBO, and that you may need to think about treating each independently if both are present.
What he reports seeing clinically: shutting off shedding by addressing inflammation
Within the single case he shares, Dr. Nemechek reports that the patient was treated with:
- Continuous rifaximin (he refers to this as “refax”) for suspected bacterial overgrowth
- Glutamine for the COVID-related gut issue, in his framework
- Fish oil and olive oil (he adds this as part of what the woman was on)
He reports that her hair loss “just stopped” at about eight weeks. He uses this to illustrate his broader point: in his clinical interpretation, sudden-onset hair loss may be “shut off” by finding and addressing the inflammation driving it.
Importantly, he also notes that if someone did not have COVID but developed digestive symptoms or food intolerance, they may have “picked up SIBO,” and he suggests rifaximin “in particular” may be needed in that situation.
A practical checklist from the video
Dr. Nemechek’s video closes with a simple, clinical-style algorithm for sudden shedding:
- Get basic labs checked (including thyroid and iron)
- Consider intense personal stress (telogen effluvium)
- Review medications or obvious causes (he mentions chemotherapy as an example that would be evident)
- If those do not fit, consider chronic inflammation—which he describes as commonly coming from bacterial overgrowth and leaky gut, and in some cases a COVID-related leaky gut that he says may involve glutamine in his approach
As he frames it, this stepwise way of thinking through sudden hair loss can help “solve most” cases he sees clinically—starting with ruling out common medical issues, then moving into stress and inflammation-related contributors.
