Low Potassium in Long COVID and Chronic Fatigue Syndrome

Most people with POTS or other orthostatic intolerance symptoms are told one thing over and over: “Eat more salt.”
And yes, extra sodium can help raise blood volume and stabilize blood pressure—it’s a key strategy for managing dizziness and rapid heart rate.

But there’s a hidden downside: when sodium intake goes up and potassium intake stays low, the imbalance can actually make symptoms worse over time. This is especially true for people with long COVID or chronic fatigue syndrome (ME/CFS), who may already have low potassium to begin with.

What Is Hypokalemia?

Hypokalemia is just the medical term for “not enough potassium in the blood” (specifically, less than 3.5 mmol/L).

Potassium is critical for:

• Muscle contraction

• Nerve signaling

• Healthy heart rhythm

When potassium is low, symptoms can include:

• Muscle weakness or cramps

• Worsening fatigue

• Palpitations or irregular heartbeat

• Worsening POTS or orthostatic intolerance symptoms

Why Might Potassium Stay Low in Long COVID?

Most research on hypokalemia comes from acute COVID-19, where low potassium is linked to a more severe illness and worse outcomes. Emerging evidence now shows that some people continue to experience low potassium well after the initial infection.

• Kidney involvement: SARS-CoV-2 can injure kidney tubules, leading to a condition called proximal tubulopathy or even post-COVID Fanconi syndrome. These conditions cause the kidneys to “leak” potassium into urine rather than holding onto it (Werion et al., 2020).

• Persistent cases documented: A 2021 case report described a patient with ongoing hypokalemia and hypomagnesemia for more than 5 months after recovering from COVID-19, likely due to continued kidney potassium loss (Alnafiey, 2021).

• Hormonal imbalance: The virus disrupts the renin–angiotensin–aldosterone system (RAAS). This imbalance raises aldosterone, which signals the kidneys to flush out potassium. In some cases, RAAS dysfunction may persist beyond the acute illness.

Together, these factors help explain why potassium can stay low in certain long COVID cases, even when people try to replace it through diet or supplements.

Potassium is Low in Chronic Fatigue Syndrome (ME/CFS)

Research shows that potassium balance may be disrupted in ME/CFS, which has important implications for fatigue and muscle function.

• A report found that people with ME/CFS had about 10% less total body potassium, and this reduction was strongly linked to fatigue severity (Burnet et al., 1996).

• More recent research confirmed these findings, showing that blood potassium levels were also low among individuals with ME/CFS (Baklund et al., 2021).

• Another study found that muscle sodium content was elevated in ME/CFS patients (Petter et al., 2022). Because sodium and potassium exist in a tightly regulated balance inside muscle cells, high muscle sodium is an indirect sign of low muscle potassium.

This imbalance can interfere with proper muscle contraction, nerve signaling, and energy production—all core issues in chronic fatigue syndrome (ME/CFS).

The Forgotten Balance: Sodium vs. Potassium

Sodium and potassium are like opposite sides of a seesaw. Every cell in your body uses the Na⁺/K⁺ pump to maintain the right balance:

• Sodium (Na⁺) moves out of the cell.

• Potassium (K⁺) moves into the cell.

When sodium intake climbs too high and potassium stays low, this pump can’t work properly.

The result?

• Muscles and nerves become overly excitable.

• Blood vessels constrict, raising blood pressure.

• Potassium gets flushed out through urine—worsening the imbalance even further.

For people with POTS or ME/CFS, this imbalance can amplify palpitations, dizziness, and fatigue, even while sodium temporarily improves orthostatic symptoms.

Ideal Sodium-to-Potassium Ratio for POTS and Long COVID

The World Health Organization (WHO) and the Institute of Medicine recommend:

• Sodium: ~1,500–2,300 mg/day (≈65–100 mmol/day)

• Potassium: ~4,700 mg/day (≈120 mmol/day)

That works out to a sodium-to-potassium ratio of about 1:2 or better, meaning you should get at least twice as much potassium as sodium.

However, most modern diets are reversed—heavy on sodium, light on potassium—with typical ratios closer to 2:1 sodium-to-potassium. For someone following a high-salt protocol for POTS, this imbalance can become extreme unless they intentionally increase potassium intake.

Top Potassium-Rich Foods for Post-Viral Recovery

Whole foods are the safest and most effective way to bring potassium levels back into range. Supplementing with potassium is generally not recommended, as it may throw off the balance of sodium. Here are some potassium-rich foods to focus on:

Fruits:

• Bananas (422mg per medium banana)

• Avocados (690mg per cup)

• Oranges (333mg per large orange)

• Cantaloupe (368mg per cup)

• Apricots (427mg per cup)

Vegetables:

• Sweet potatoes (542mg per medium potato)

• Spinach (419mg per cup cooked)

• White potatoes (610mg per medium potato with skin)

• Tomatoes (400mg per cup)

• Brussels sprouts (342mg per cup)

Other Good Sources:

• White beans (595mg per cup)

• Salmon (534mg per 3.5 oz)

• Plain yogurt (380mg per cup)

• Coconut water (480mg per cup)

Electrolyte Products: What to Look For

Many electrolyte powders and drinks are sodium-heavy, designed for athletes who sweat a lot. These often contain 300–500 mg of sodium but very little potassium.
For someone with POTS or orthostatic intolerance, this can push the balance even further out of range.

When choosing a product:

• Look for at least 2x as much potassium as sodium, or aim for a 1:1 balance minimum if you’re actively increasing salt for POTS.

• Coconut water can be a natural option—moderate sodium with decent potassium.

Key Takeaways

• Hypokalemia (low potassium) is common in long COVID and ME/CFS, especially in patients with POTS or high-salt diets.

• Persistent low potassium may result from kidney dysfunction, RAAS imbalance, or post-viral tubular injury.

• Most patients focus heavily on increasing sodium, but potassium must rise alongside sodium to maintain balance and prevent worsening symptoms.

• Aim for twice as much potassium as sodium through diet and carefully selected electrolyte products.

• Whole foods like potatoes, avocados, bananas, spinach, beans, and coconut water are your best sources.

References

Alnafiey MO, Alangari AM, Alarifi AM, Abushara A. Persistent Hypokalemia post SARS-coV-2 infection, is it a life-long complication? Case report. Ann Med Surg (Lond). 2021;62:358-361. doi:10.1016/j.amsu.2021.01.049

Werion A, Belkhir L, Perrot M, et al. SARS-CoV-2 causes a specific dysfunction of the kidney proximal tubule. Kidney Int. 2020;98(5):1296-1307. doi:10.1016/j.kint.2020.07.019

Burnet RB, Yeap BB, Chatterton BE, Gaffney RD. Chronic fatigue syndrome: is total body potassium important?. Med J Aust. 1996;164(6):384. doi:10.5694/j.1326-5377.1996.tb122076.x 

Baklund IH, Dammen T, Moum TÅ, et al. Evaluating Routine Blood Tests According to Clinical Symptoms and Diagnostic Criteria in Individuals with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome. J Clin Med. 2021;10(14):3105. Published 2021 Jul 14. doi:10.3390/jcm10143105