A pulse oximeter clips onto your finger and shines light through your skin to estimate how much oxygen your blood is carrying. Because it works with light, the color of the skin it shines through can affect the result. That concern became urgent during the COVID-19 pandemic, when millions of people were checking their oxygen at home, and regulators in the US and the UK have been working on it since.
This guide sets out what they have found and what they advise. It does not go beyond what they say: we are not doctors, and what your own readings mean is a question for yours.
What the FDA has said
In February 2021 the FDA issued a safety communication telling patients and health care providers that “although pulse oximetry is useful for estimating blood oxygen levels, pulse oximeters have limitations and a risk of inaccuracy under certain circumstances.” It listed the factors that can affect a reading: poor circulation, skin pigmentation, skin thickness, skin temperature, current tobacco use, and fingernail polish.
Its current position, repeated in its January 2025 announcement, is that “current scientific evidence suggests there are some accuracy differences in pulse oximeter performance between individuals with lighter and darker skin pigmentation.”
Between the two, the FDA:
- Funded two studies in 2022, with academic partners, of how oximeters perform in adults and in children, using simultaneous oximetry measurements and an objective measurement of skin pigmentation.
- Held two public advisory committee meetings, in November 2022 and February 2024, on “ongoing concerns that pulse oximeters may be less accurate in individuals with darker skin pigmentation.”
- Published a discussion paper in November 2023 on how oximeter testing could take skin pigmentation into account.
The FDA’s 2025 draft guidance
In January 2025, the FDA published draft guidance for manufacturers, Pulse Oximeters for Medical Purposes, with new recommendations for how oximeters should be tested and labeled. The key proposals, in the FDA’s words:
- “Gathering clinical data (e.g., controlled desaturation laboratory study or, in certain cases, real-world data) to evaluate device performance accuracy across the range of skin pigmentations”
- “Increasing the number of clinical study participants”
- Using both a subjective scale (the Monk Skin Tone Scale) and an objective measurement (the individual typology angle) to assess each participant’s skin tone
- If a device has shown it performs comparably across skin tones, a prominent statement on its labeling saying so
The FDA also proposed a public webpage listing every FDA-cleared oximeter for medical purposes that has shown comparable performance across skin pigmentations. And it said it expects that some oximeters already on the market may meet the new criteria without hardware or software changes, in which case it intends to review updated labeling quickly.
What the draft does not do
Two limits are worth being clear about.
It is still a draft. When we checked the FDA’s guidance page, the document was still marked as a draft, “Not for implementation.” Everything above, including the labeling statement and the public list, is a proposal until the FDA finalizes it.
It does not cover sport or wellness oximeters. The FDA says the draft “does not apply to pulse oximeters that are sold as general wellness products or sporting/aviation products, which are not reviewed or evaluated by the agency prior to being available to the public.” It also notes that “a large number of pulse oximeters available over the counter or for sporting/aviation are considered general wellness products” that the FDA has not evaluated for clinical use. That is a large share of what is sold online, and it is why our pulse oximeter picks only include oximeters cleared by the FDA as medical devices.
What the UK has found
The UK government commissioned an independent review of bias in medical devices, which reported in March 2024. Pulse oximeters were the reason it was set up. On the evidence, the review is direct: “We found extensive evidence of poorer performance of pulse oximeters for patients with darker skin tones. These devices over-estimate true oxygen levels in people with darker skin tones to a greater extent than with lighter skin.”
On harm, it drew a distinction between countries. It reported that studies in the US health system had found a strong association between this bias and delayed recognition of disease, delayed or denied treatment, and worse outcomes for Black patients compared with White patients. It “did not find any evidence from studies in the NHS of this differential performance affecting care but the potential for harm is clearly present.”
Its first recommendation was immediate action so existing oximeters can be used “safely and equitably for all patient groups across the range of skin tones.” That included asking the MHRA, the UK regulator, to strengthen its guidance for patients and caregivers using oximeters at home.
The MHRA’s own guidance for health professionals, published in March 2021 and so older than the review, says that “it is possible that patients with lighter skin may have small differences in the result reported when compared to those with darker skin,” and that it was “not aware of any incidents where skin colour has had an adverse effect on the use of pulse oximeters when providing effective clinical care.” The review, three years later, went further, and recommended that the MHRA strengthen exactly this guidance.
What they advise you to do
None of these bodies tells people to stop using pulse oximeters. The UK review says it “would definitely not advise curtailment of their use in patients with darker skin tones.” Their advice is consistent, and it is about how you use the number:
- Keep using it if you have been given one. NHS England’s home oximetry leaflet says oximeters “may show readings higher than the level of oxygen in your blood” in people with brown or black skin, but that “you should still use your pulse oximeter if you’ve been given one. The important thing is to check your blood oxygen level regularly to see if your readings are going down.”
- Watch the trend, not just one reading. The UK review recommends that health professionals advise patients using an oximeter at home “to look at changes in readings, rather than just a single reading.” The MHRA makes the same point to clinicians: “the relative change in a patient’s reading may be of greater significance to clinical management than the absolute value.”
- Watch how you feel, too. The UK review says patients should also look out for “shortness of breath, cold hands and feet, chest pain and fast heart rate.” The FDA says: “Do not rely only on a pulse oximeter,” keep track of your symptoms, and contact a health care provider if you are concerned about a reading or your symptoms are serious or get worse.
Writing your readings down, with the date and time, makes the trend visible. Our guide to using a pulse oximeter covers how to take a reading that is worth writing down, and what the NHS and FDA say about when to get help.
Choosing an oximeter with this in mind
Until the FDA’s draft is finalized, there is no official list of oximeters proven to perform equally across skin tones, and we will not guess at one. Some manufacturers make claims about skin tone accuracy on their own listings; we have not tested any oximeter and cannot confirm those claims.
What you can do today is choose an oximeter that the FDA has reviewed at all. A device sold “for sport and aviation use only” has had no independent accuracy check for medical use, on any skin tone. A cleared device has. When the FDA’s list of oximeters with comparable performance across skin tones is published, we will use it.