Can You Be Allergic To Sunlight?
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Can You Be Allergic To Sunlight?

♪ INTRO ♪ We all know that the sun can be dangerous. The UV radiation that beams down on you at the beach can damage your DNA, giving you painful burns and eventually, possibly cancer. That should be reason enough to wear sunscreen. But for some people, sunlight means hives or itchy rashes. That’s right, you can be allergic to the sun. If you have a condition called solar urticaria, big, itchy welts develop within minutes of sun exposure. These hives die down within a day, but as you can imagine, this disease seriously puts a damper on going outdoors. Scientists don’t fully understand why this happens, but they think it’s pretty similar to how your immune system might overreact to peanuts if you have a food allergy, or to pollen if you have seasonal allergies. In those cases, the immune system sees allergens like peanut or pollen proteins as foreign invaders, and arms special cells with antibodies that recognize them. So when those proteins pop up again, those immune cells spring into action and release a bunch of histamine. Histamine is a compound that spurs blood vessels to become leaky and muscles to contract, which helps more immune cells flood in and fight off any junk, but also causes the telltale symptoms of an allergic reaction, like red blotchiness or swelling. In solar urticaria, that same process seems to happen, but the molecule that’s causing the immune system freakout is a mystery. The leading theory is that some people have light-absorbing molecules in their skin that transform into allergens when the right wavelength hits them. In severe cases, people can even develop welts from lightbulbs or when they’re wearing thin clothing outdoors, or even go into anaphylaxis. The good news is that this sun allergy is extremely rare. Of all the people who get hives, only about half a percent of them do because of the sun. But there’s a similar condition that affects as many as 10 to 20 percent of some human populations called polymorphous light eruption, or PMLE. It’s also a sun-triggered rash. But, as the name “polymorphous” suggests, it can be a bit of everything, from itchy, fluid-filled blisters to simple raised bumps or red patches. Instead of showing up almost immediately, like solar urticaria, it can take hours or even days and it sticks around for a while, too. How the immune system goes overboard in this case is even less well understood. But because of the delayed timing, it’s thought to be similar to a poison ivy reaction, which activates immune cells called helper and killer T cells and causes inflammation. Except instead of an oily sap, the trigger in PMLE is another mysterious light-sensitive molecule. Fortunately, PMLE doesn’t cause scarring, and with repeated exposure to the sun over time, the rash outbreaks often improve. So, while there may not be sunlight-fearing vampires roaming the planet, there are some people who need to live a little bit like them. Thanks for asking, and thanks to all of our Patreon patrons who keep these answers coming! If you want to learn more about allergies, we have a video where Michael goes deeper into the science of these immune system mishaps. ♪ OUTTRO ♪


  • puppy lover

    ive never had this before and i always tan and just today i started to scratch my head and face and felt bumps and it itches.. what is it???

  • Jamie Lilac

    You can indeed be allergic to the sun, it's not an actual allergy but your skin reacts to the skin as it would any other reaction. I have PMLE and you have to wear steroid cream every time you are exposed to the sun.

  • Galia De Koster

    I have solar urticaria and life has become harder…i used to love gardening and was a big swimmer…now i cant…if i go outside even on cloudy days I must wear jeans always shoes hoody as now it attacks my face and in summer i sweat with all this on…it is a terrible life changing disease.

  • Fox

    Here's some facts about me:
    I actually have a Sun allergy (the polymorphic one not the really bad one).

    I'm also more naturally nocturnal.

    I'm a phlebotomist.

    Oh and I also do love capes, and bats.

    Am I vampire? Well That's for you to decide.

  • Marie Huynh

    I have both. Excessive exposure (minutes of intense sun) results in a near-immediate reaction, then continue with swelling and additional flu/cold-like symptoms for at least a week. Scars from the rashes and blisters take a month or more to fully heal. Thus I don't go out much, but if I do, leather clothing is the best barrier. Most of the clothing labeled UPF50+ is a lie. It's helpful to take antihistamines before leaving the house so I buy the giant Costco bottles of loratadine.

  • Izuku Midoriya

    He left out erthroproaticporpheria or EPP you get blisters and they scar; when you go into the sunlight with short sleeves or thin clothing you feel like lava is being poured on you. I know this because I have it. Sunscreen does absolutely nothing and people think I am lying (I am at a new school so I tell them "wait for spring to roll around,I will still be wearing jackets."

  • MutantCreeper

    One time I took a certain medicine for my Ulcerative Colitis and it made me sensitive to the sun and gave me hives and as that happened, they gave me new medicine that wouldn't cause it and I still have minor hive scars to this day on my hands and arms but they're just a weird skin pigment thing when I get too hot or too cold.

  • Caleb Jesse

    short name being allergic to the sun is a rare disease I have it I have E.P.P. or also known as Erythropioetic protoporphyria

  • Xalio Nightmare

    I have it
    i itch when i am out and people think im dirty for itching so much
    i cant move and it feels as if my skin is burning

  • Ahrrym 8rien

    Okay so it's PMLE. Thank you for this video. It had always concerned me. Now it will simply irritate me all summer, but at least ill know why from now on.

  • FlooflePoof

    I have pmle it hasn't improved at all doctors found out I had it one day I got burnt and it started to blister I can barely be outside for more then 40 minutes

  • Hannah Eliza C

    I wonder I suffer from – no idea if it is solar urticaria or PMLE – it's only over the past two or three years it's started. I get terrible hives on my arms, shoulders and feet and my skin stays burnt for ages. I even put SPF 30 or 50 on and it doesn't make much difference at all to the hives I get. It's worrying me because it's supposed to be as hot and sunny as it is right now where I live for the next 4 months and if I'm already this bad from about 6 odd days of bright hot sunlight then I don't know how I'm gonna survive.

  • Official Silke F

    I am allergic to sunlight. Stupid question. Doctors don't know what is going on. I'm like a vampire. If I go into the sun, my eyes change color different on each eye and my skin is morphing.

  • 6ix9ine Kimberly

    I have lupus and it's like skin cancer so I can't be in the sun.What sucks is that in the summer I have to go inside and with no ac🙃

  • Kdkdjj Mahi

    I am allergic to the sun, it’s disappointing. Also my Best friend is she gets many hives, but for me I sneeze over 5 times. I only sneeze if the sun it
    Toward me or to my side. But behind I don’t get a reaction.

  • Ginger_Sweet

    We’re in the middle of a heat wave I haven’t been out in the day in over three months because I can’t put the 3 to 4 layers of clothing necessary to protect myself I have opaque window coverings and I can’t use any lights in my home that are uv like many leds can be they replaced all the elevator lights with these uv led cfl bulbs so just trying to get downstairs will cause hives and a rash many businesses also use these bulbs to save on energy costs sometimes it feels like the whole damn world is just trying to make life harder -_-

  • pen chhenglun

    I can guarantee that this exist since I've experienced it myself. While this condition was not heard of back in the 2010 – 2016 (where I experience PMLE), my friends thought I was joking around and said I was weird. –_– the only person that believe me after 2 years of experiencing PMLE is my mom since she always witness me having it whenever I'm expose to the sun for more than 7 mins. well, in my experience it did get better after experiencing for 6 years straight. It sucks back in the old way when I was such an athletic person but despite having PLME, I participate in many sports activities without giving a damn and thank goodness that I didn't have a serious PLME or else I might actually died from being stubborn.

  • Abby M

    I have solar urticaria and it sucks. I'm a freshman in high school and I'm not able to play sports, or go outside without my skin breaking out and it burns and itches sometimes and I have an EpiPen and a pill to take before being exposed to sunlight. I used to not be like this and it's honestly changed my life alot and it sucks.

  • Eliana Robinson

    I AM allergic to the sun. For ten years now, induced through pain killers and poor treatment for a river fever by an incompetent doctor that damaged my immune system. I don't break out in whelps but burn badly and instantly I use to have to wear full face and body cover up clothing with sunglasses now I only have to wear sunglasses but I still suffer bad burning on my face and eyes, this has been since proven to be worsen by taking the same pain killers (even in moderation) as it aggravates my confused system. I don't have an issue with lights and never have but fan forced heaters and exercise can cause my face to burn like I've held hot irons to them, and I mean badly burn, as its more a internal thing rather than in my skin directly. Its called Photosensitivity a subsection of the conditions disguised in this video but slightly different. Its been proven that extremely monitored food habits and improving my over all health and above all refrain from any medicines can improve my condition greatly, though its not proven yet I might one day no longer have to wear sunglasses.That's my great hope. Photosensitivity doesn't get support or help and in most doctor's clinics and government aspects isn't even accepted as a condition. It IS a real condition and has incredible disruptive and painful consequences to the person's life.

  • Eliana Robinson

    As stated in my last comment mine is an immune issue and I don't have much help from doctors so I'd like to see the video mentioned in the last few seconds of this video….where can I see it?

  • Blind Paws

    Doctor diagnosed me with SU. Anyone have Any recommendations on a close or hats. Trying to find something that will cover my face but that is easy to breathe with

  • xcxzozo

    I have a couple medications to help with the itching plus before going out I put on loooooots of sunscreen and if I’ll be out for awhile I bring my uv protectant umbrella

  • Kevin O'Neill

    Out for half a hr on 4/11 with a t-shirt. Dreading the summer, while looking at my arms not wanting to scratch.

  • Sammy Cat:3

    I’m allergic to the sun I stay inside but I have to wear equipment to go outside I have to go outside at night

  • Banana Phone

    I have some undiagnosed condition that makes me very sensitive to the sun, but I rarely break out due to it. I've had this issue at least since childhood (as far back as I can remember). Direct sunlight on my skin is extremely painful and bright light of any kind is painful to my eyes. Up until recently, I would just avoid sunlight by going out at night and sleeping most of the day, but life has always forced me to go out during the day on occasion for certain tasks. By the end of said day, I would be so incredibly exhausted and I've tied that exhaustion to sunlight. Recently I've begun trying to find ways to be able to get out into the daytime without feeling like I'm literally going to catch fire. Sun umbrella, zinc oxide sunscreen (all the others break me out for some reason), quality polarized sunglasses and going to be tinting the windows in my car. The sunscreen (SPF50 25% zinc oxide) doesn't stop the pain, but it does reduce it some. The sun umbrella does wonders, however, is not nearly big enough, plus is an annoyance to carry. I can't seem to find a sun umbrella big enough, I've considered building my own, but I doubt I could make it lightweight enough. Apparently, I very easily tan because I have always avoided direct sunlight yet have always had a slight tan. Recently, after wearing sunscreen on exposed areas, I have very quickly lost my tan. I'm turning pale pretty quick lol. Yes, I am taking vitamin D.

  • wolf spirit

    Just yesterday it was really bright i wear glasses cause of my almost bad eye sight but as soon as I stepped out the light made my eyes heart and later triggered a small throbbing headache though I was on my smartphone the night before and a short time before I went outside

  • azulm0rena

    Well it looks like im not the only one. But as far as I have been researching in to it. It’s genetic 100%. Since my middle child has it too. But as far as I know, it has to do with the skin pigmentation and the body immune system too. Each one plays a part in it. I’ve try getting asunto tan and all I get is red but no tan, and minutos after the hives start to come out only in the arms and legs. You can bring down the hives with an ice pack or some Olivera gel. I usually cover up in Sumer

  • AirFire18

    I’m allergic, my mother has the same problem. But it varies.. the further south i travel – the less of an issue i seem to have.

  • Mothra Kaiju

    I think I have this I get little sharp shooting stinging pin pricks get all over my body but I also get it sometimes when I have clothes on so maybe I’m allergic to extreme temperature changes that’s is very quick such as walking out of an air conditioned house to a very hot dry outdoors with the sun baking the ground I rarely ever get red nor any type of rash it just really hurts.

  • Breets Shop

    I developed this as an adult in my early 20s. I totally thought it was from the sand at the beach but then one day I broke out sitting in sun on my deck. Just found out a month ago it’s from the sun. I have a breakout now from doing yoga outside on a sunny day

  • Vixinaful

    Basically it's autoimmune which makes sense since I have an autoimmune disease. Stop eating gluten that triggers autoimmune diseases and you're fine.

  • Emperor Louis The Retard

    I used to have a sunlight allergy but with the help of a mask i made out of stone and a reddish amber gem i was able to overcome that allergy and turn into an ULTIMATE LIFE FORM!

  • Saraid Muñoz

    Cheers for the Video! Apologies for butting in, I am interested in your opinion. Have you considered – Trentvorty Urticaria Victory Theorem (erm, check it on google should be there)? It is an awesome exclusive product for curing hives without the headache. Ive heard some unbelievable things about it and my old buddy Taylor at last got cool results with it.

  • CalienteFrijoles

    It sucks bc even with sunblock I’ll get this rash, so basically I’m in a jacket year round. I gotta say it’s built up my heat resistance but not like in a superhero kind of way; I’ll still catch fire. Honestly 78 degrees Fahrenheit is ideal for me

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