How Henna and Nail Polish Alter the Oximeter Readings

Overnight oximetry testing allows us to have a continuous reading of the blood saturation level of a patient. The oximeter device act as a useful and a primary tool in health care settings. However, there are certain conditions that are to be taken in consideration during the testing. If the ideal situation is not present then the readings are most likely to be flawed.

Understanding the workings of a Pulse Oximeter:
Before the introduction of pulse oximetry, the saturation level of oxygen was observed through the tedious and invasive method of blood samples. But with this device the blood is monitored for oxygen saturation through skin, the monitor and readings give a clear indication of patient’s heart rate and oxygenation.

There are many factors that have a direct affects on the readings of pulse oximeter testing and among them are the uses of nail polish and henna.


  • Nail Polish:

A patient who is wearing nail polish will have the wrong readings. It’s better to switch the probes to nails with no polish or choose an entirely another application site like ear lobes. The findings that nail colors affect the results of pulse oximeter testing is a result of various tests conducted to ensure it. Research conducted by Coté and coworkers discovered that nail polish can affect the reading of oxygen saturation by a huge margin. Test conducted showed a decrease by 97% to 87% as compared to the original Spo2.


  • Henna:

Henna one of the most commonly used dye all over the world. A large number of Asian women apply it on their hands and some men apply it as well. Henna’s scientific name is Lawsonia inermis and when it is freshly applied on skin, it causes a discoloration on the skin.

A pulse oximeter works by monitoring blood by the transmission of light at two wavelengths and if there’s anything that acts as a hindrance in the path of light, it affects the readings. Now a henna application on the hands is dark skin pigmentation and instead of letting these two wave lengths pass the skin, it ends up absorbing it and only allowing the infrared to infiltrate. The results are obviously incorrect when the device is unable to function as it should.

Moreover henna is difficult to remove. It is the kind of dye that penetrates our skin and cannot be washed off or removed just by using some common chemicals. The most one can achieve is to soften or maybe dull the dark color of the henna but it still remains penetrated deep within the skin. The only way to have correct readings is by changing the area of application.

As we mentioned formerly, it is very necessary to take the correct readings because finding out the blood saturation level at the right time can help save someone’s life. It is highly recommended to get your overnight pulse oximetry testing by an IDTF that is informed with the procedures of testing.