We are independent & ad-supported. We may earn a commission for purchases made through our links.

Advertiser Disclosure

Our website is an independent, advertising-supported platform. We provide our content free of charge to our readers, and to keep it that way, we rely on revenue generated through advertisements and affiliate partnerships. This means that when you click on certain links on our site and make a purchase, we may earn a commission. Learn more.

How We Make Money

We sustain our operations through affiliate commissions and advertising. If you click on an affiliate link and make a purchase, we may receive a commission from the merchant at no additional cost to you. We also display advertisements on our website, which help generate revenue to support our work and keep our content free for readers. Our editorial team operates independently from our advertising and affiliate partnerships to ensure that our content remains unbiased and focused on providing you with the best information and recommendations based on thorough research and honest evaluations. To remain transparent, we’ve provided a list of our current affiliate partners here.

What is Fluorescein?

Mary McMahon
Updated Jan 28, 2024
Our promise to you
AllTheScience is dedicated to creating trustworthy, high-quality content that always prioritizes transparency, integrity, and inclusivity above all else. Our ensure that our content creation and review process includes rigorous fact-checking, evidence-based, and continual updates to ensure accuracy and reliability.

Our Promise to you

Founded in 2002, our company has been a trusted resource for readers seeking informative and engaging content. Our dedication to quality remains unwavering—and will never change. We follow a strict editorial policy, ensuring that our content is authored by highly qualified professionals and edited by subject matter experts. This guarantees that everything we publish is objective, accurate, and trustworthy.

Over the years, we've refined our approach to cover a wide range of topics, providing readers with reliable and practical advice to enhance their knowledge and skills. That's why millions of readers turn to us each year. Join us in celebrating the joy of learning, guided by standards you can trust.

Editorial Standards

At AllTheScience, we are committed to creating content that you can trust. Our editorial process is designed to ensure that every piece of content we publish is accurate, reliable, and informative.

Our team of experienced writers and editors follows a strict set of guidelines to ensure the highest quality content. We conduct thorough research, fact-check all information, and rely on credible sources to back up our claims. Our content is reviewed by subject matter experts to ensure accuracy and clarity.

We believe in transparency and maintain editorial independence from our advertisers. Our team does not receive direct compensation from advertisers, allowing us to create unbiased content that prioritizes your interests.

Fluorescein is a fluorescent dye which is used in a number of different applications in the sciences and medicine. In pure state, fluorescein is a red or orange powder which is dissolved in alkaline solutions to make up a yellow solution which will glow green. In addition to using straight fluorescein, researchers also work with various derivatives of the compound which are designed to conjugate to specific types of molecules and perform other functions.

In medicine, this compound has a broad range of uses. Ophthalmologists use it in eye exams, staining the eye with the dye to look for signs of tears in the cornea, and they can also use it for fluorescein angiography of the retina, using the dye to look for leaks inside the blood vessels in the eye. The chemical can also be used as a tracer in other areas of the body, and it is utilized in microscopy and as a stain. In addition, fluorescein derivatives are used in the lab to identify compounds in fluid samples, with the chemical attaching to specific proteins to act as a flag.

In laboratory science, fluorescein can be used for protein labeling, and in a number of other tasks. Outside the lab, this dye was historically used to trace river flow and flows of pollutants, although it has been replaced in some regions due to concerns about the environmental impact of these practices. This compound is also used in dye lasers and some other scientific instruments which need to be able to fluoresce.

Oceanographers and hydrologists have historically used fluorescein to trace the flow of currents through bodies of water of interest. In this case, a load known as the “point source” is released in a set location and followed as it moves through the water. In addition to providing data about current flow, the movement of the fluorescein can also be used to trace contaminants, by tagging the contaminant with the compound and watching to see where it goes. This information can be used in environmental cleanup efforts.

Several chemical companies manufacture fluorescein and derivatives of this compound, such as fluorescein isothiocyanate. These companies can sell the product packaged as powder or solution, in various sizes to meet the needs of users. This compound is one of the most widely used fluorescing molecules, and numerous photographs featuring this chemical compound in action can be found on scientific websites.

AllTheScience is dedicated to providing accurate and trustworthy information. We carefully select reputable sources and employ a rigorous fact-checking process to maintain the highest standards. To learn more about our commitment to accuracy, read our editorial process.
Mary McMahon
By Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a AllTheScience researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

Related Articles

Discussion Comments

By anon280655 — On Jul 19, 2012

Can you tell me if the fluorescein dye that is given IV has adenosine in it? I am very allergic to this compound and am due to have a fluorescein angiogram in a few weeks.

By Izzy78 — On Oct 02, 2011

@matthewc23 - I am with you. I have only heard about fluorescein in biology. I think it was used a lot to figure out how different pathways in our cells worked. For a long time, scientists couldn't figure out how proteins were formed in our cells. Eventually, they were able to put fluorescent markers on different compounds and found that ribosomes were responsible for moving into and out of the cell nucleus and creating proteins.

You mentioned fireflies. I guess the same principle would apply of a reaction causing a release of light, but I don't think bioluminescence is really fluorescent is it? Just normal light energy.

By matthewc23 — On Oct 01, 2011

@jcraig - I had no idea that fluorescein could be used for such a wide range of things. When I have seen it used, it was always in genetics experiments. In those cases, you had to put cells under UV light to see the glow, but I'm not sure how it would work in larger quantities like the river example from the article.

As for what it is made of, I just looked it up, and it is a normal organic compound of carbon, hydrogen, and oxygen. I couldn't tell you how it reacts to make a glow, though. Somehow it would have to make a compound that released energy as light. I think it would kind of be like a lightening bug lighting up.

By kentuckycat — On Oct 01, 2011

Thinking about glowing things, is fluorescein used to make the glow sticks you can buy at fairs and concerts? Seems like it would be a reasonable guess. I guess I would have the same question about glow in the dark paints and things like that, too.

Is this stuff something that you could buy online somewhere and play with, or is it considered too dangerous to sell to the public? I would think you could have a lot of fun with it if you had some.

By jcraig — On Sep 30, 2011

Is fluorescein detection possible with the naked eye, or do the molecules only glow in the dark or under something like a dark light or ultraviolet radiation?

Also, what compounds are used to make fluorescein? Does it have fluorine in it? Just guessing that from the name. I guess I have never really thought about what makes something glow before.

By Mykol — On Sep 30, 2011

Every time I go to the eye doctor for an exam, he always puts drops in my eyes and I would always have a yellowish residue when I wiped my eyes the rest of the day.

Now I know that is a fluorescein dye that he uses to check my cornea. Even though these drops don't really sting when they are put in my eye, I knew they weren't just regular eye drops.

It is amazing how dyes like this can really make any abnormalities show up. I wonder if the drops that contain the fluorescein are also what makes my eyes dilated, or if they use something else for that?

Mary McMahon

Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a...

Read more
AllTheScience, in your inbox

Our latest articles, guides, and more, delivered daily.

AllTheScience, in your inbox

Our latest articles, guides, and more, delivered daily.