25 Rarest Medical Conditions You Will Never Believe

Posted by , Updated on January 5, 2024

The term “medical condition” is very broad because it includes all diseases, illnesses, and disorders. Many people are well aware of the more common medical conditions like diabetes, asthma, and hypertension. 

However, there are quite a few rare medical conditions that some doctors don’t even know exist. Since these conditions are so uncommon, it may take years for a patient to get properly diagnosed. As far as treatment goes, this could take even longer. 

That is why it’s so important to put a spotlight on the top 25 Rarest Medical Conditions Ever Recorded. Sharing information about the symptoms will help these rare medical conditions become more widely recognized.


Sleeping Beauty Syndrome

Sleeping Beautyhttps://www.healthline.com/health/kleine-levin-syndrome

It’s quite normal to feel tired. In fact, the majority of people often feel tired throughout the day. The average person normally takes a 20-minute nap to help them rejuvenate. A person with sleeping beauty syndrome can sleep up to 20 hours a day and still feel tired.

The rare disorder also causes a person to feel confused and groggy. Stimulant pills have been used as a way to help reduce sleepiness and promote a more active lifestyle.


Alexander Disease

Heart Beat https://rarediseases.org/rare-diseases/alexander-disease/

Scientists originally thought that Alexander disease typically occurred during the early stages of life. However, after further research, they concluded that a person can develop it at any age.

Since Alexander disease is estimated to occur in one out of every million births, it may take years for a patient to get properly diagnosed. A few common symptoms include a thin scalp, lowered heartbeat, headaches, and vomiting.




Eating another human being seems like a completely barbaric, unnatural thing to do. However, there are communities in New Guinea that participate in a form of cannibalism as part of a funeral ritual.

Scientists have found that the people who consumed contaminated human brain tissue contract the Kuru disease. This extremely rare medical condition attacks part of the brain responsible for coordination and balance.


Moebius Syndrome


A person’s face is perhaps one of the most important parts of the body. It’s how most people communicate and it gives a person their outer identity. That is why researchers are trying to find a  treatment for Moebius syndrome.

This rare neurological condition affects the muscles that control facial expression and eye movement. Infants with this condition tend to need a feeding tube in order to consume enough nutrition to survive. 




If one parent passes on to their child a specific abnormal gene, that child will get Porphyria. This rare condition is basically a group of disorders created by a buildup of natural chemicals in the body.

Some symptoms may include abdominal pain, diarrhea, vomiting, and hallucinations. Luckily, there is a treatment and it involves intravenous infusions. Scientists are also researching a possible drug version treatment option.


Alice in Wonderland Syndrome


Alice in Wonderland syndrome received its name from the scene in the movie where Alice drinks a magic potion and it makes her shrink. This is because that is exactly how people with AWS feel.

The medical condition causes a person to feel much larger or much smaller than they actually are. It has also been proven to cause episodes of distorted perception and disorientation.

Thre is currently no cure. Doctors have said the best way to treat someone with this condition is to simply make them feel comfortable.



Sick babyhttps://www.webmd.com/children/progeria#1

Progeria is a deadly disease that affects one out of every four million people worldwide. This extremely rare genetic condition causes a child’s body to age prematurely. The oldest person ever recorded with Progeria died at the age of 26.

Children with this condition often suffer from heart problems and strokes. Sadly, there is no cure but researchers are actively looking for a treatment to help fix damaged cells and ease symptoms.



Itchy Skinhttps://www.healthline.com/health/morgellons-disease

Small particles crawling out of your skin may seem like something out of a horror movie, yet the rare medical condition known as Morgellons brings this nightmare to life.

Scientists have concluded that people with this condition often exhibit sores and have the feeling of something crawling or stinging their skin. Doctors frequently prescribed different kinds of antibiotics to try and treat this condition.


Water Allergy


Water is literally everywhere. Not only is your body mostly made up of water, but it also covers around 71% of the earth’s surface. As crazy as it may seem, getting diagnosed with a water allergy is a very real thing.

This rare medical conditional makes doing everyday activities like drinking water, showering, or going swimming almost impossible. Doctors have prescribed medications such as an antihistamine to help treat hives after being in contact with water.



Munchausen Syndrome By Proxy

Sick Child https://www.uofmhealth.org/health-library/hw180537

Hearing that their child has a medical condition is a parent’s worst nightmare. For a caregiver with Munchausen syndrome by proxy, that could be their dream come true.

MSP is a psychological disorder characterized by a person seeking medical attention for a healthy child. People with this disorder often exaggerate illnesses or completely invent symptoms.

Caregivers diagnosed with this illness are encouraged to seek long-term counseling.


Lesch-Nyhan Syndrome

sore handshttps://medlineplus.gov/ency/article/001655.htm

People inherit many different kinds of qualities that make a person uniquely them. The majority of people inherit things like eye color, sleeping styles, and hair texture. However, Lesch-Nyhan syndrome can also be inherited.

This rare disorder causes the body to overproduce uric acid. Symptoms include inflammatory arthritis, kidney stones, and bladder stones. Doctors often recommend Lesch-Nyhan syndrome patients to use the same medicine that helps to treat gout.


Marie Antoinette Syndrome

white hairhttps://jamanetwork.com/journals/jamadermatology/article-abstract/712060

Marie Antoniette was the last queen of France before the French Revolution. She went down in history for her lavish lifestyle, fashion, and big white hair. That is why the rare medical condition that makes hair suddenly turn white is named after this infamous queen.

No one wants to get grey hair prematurely. So, luckily, the disease can be successfully treated with steroids or a good box of hair dye. 



Hairy facehttps://www.dermnetnz.org/topics/hypertrichosis/

In some parts of the world, being hairy is a form of sex appeal. However, extreme amounts of hair could be a symptom of hypertrichosis. The rare medical condition is characterized by an abnormal amount of hair growth over the whole body.

This could include hair growing all over a person’s face, neck, back, arms, or legs. While there is yet to be a cure discovered, the effects of the disease can be reduced through hair removal treatments.



Elephant https://www.who.int/news-room/fact-sheets/detail/lymphatic-filariasis

The Elephant Man is a historical drama released in 1980 that depicts a man born with Elephantiasis, a congenital disorder. The movie helped to shed light on this very real disease that transforms a person’s appearance.

The rare medical condition is transmitted to humans through mosquitoes. Once infection occurs, the person’s limbs harden and parts of their muscle tissues begin to swell. This condition is chronic, yet treatable by professionals in early stages.


Xeroderma Pigmentosum

UV https://ghr.nlm.nih.gov/condition/xeroderma-pigmentosum

Our sun is not only a powerful star, but it’s also one of the reasons there is life on earth. It provides energy to plants through ultraviolet radiation, which leads to plants giving us oxygen.

Even though UV lights can be used for good, some people are negatively affected by the sun’s powerful rays. Xeroderma pigmentosum is a genetic disorder that makes it difficult for the body to repair DNA damage caused by the sun.

Some symptoms are dry skin, changes in skin pigmentation, and severe sunburn after brief exposure to the sun.


Fragile X Syndrome


Fragile X syndrome, also known as FXS, is a genetic condition caused by a mutation of the FMR1 gene. Scientific researchers have discovered that this rare medical condition more severely affects males.

Some of the symptoms include learning disabilities and cognitive impairment. No cure has been found for the condition; treatments currently include therapy services and appropriate forms of intensive learning. 


Cotard’s Delusion

depression https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4271387/

Everyone has experienced a day where no matter what they do, they feel as if they don’t exist. It’s definitely not a good feeling, yet someone with Cotard’s delusion feels this way all the time … and much worse.

This rare medical condition has a delusional effect on a person, making them feel like they are already dead or do not exist at all. 

Researchers have found that depression is the most common diagnosis given to people who actually have Cotard’s delusion.


Myostatin Related Muscle Hypertrophy


The majority of rare diseases are quite agonizing and at times even deadly. However, the rare medical condition myostatin-related muscle hypertrophy stands out from the rest.

It is caused by a mutation in the MSTN gene, which leads the body to actively reduce fat and increase skeletal muscle size. People who have been diagnosed with this condition tend to have twice the usual amount of muscle mass and increased strength.


Fibrodysplasia Ossificans Progressiva


Muscle tissue is a very soft tissue that gives muscles the ability to contract and rise. For a person diagnosed with fibrodysplasia ossificans progressiva (FOP), their muscle tissue, connective tissue, and ligaments are slowly replaced by bone.

Over time, this rare disease makes it almost impossible for a person to move. Most patients with FOP become bedridden by the age of 20 and have an average life expectancy of 40 years. 


Capgras Delusion


Imagine living in a world of constant fear that one of your loved ones has been replaced by an identical imposter. For someone with Capgras delusion, that fear is a reality.

Some researchers think this rare medical condition is caused by both physical and cognitive changes in the brain. Unfortunately, there aren’t any cures or treatments currently used to effectively remove Capgras delusion.


Proteus Syndrome


One of the more agonizing conditions for a person to get diagnosed with is Proteus syndrome. This rare medical disease causes a person’s bones to overgrow.

For the majority of people with Proteus syndrome, their bones tend to grow out of proportion compared to the rest of their body. While the severity of the disease varies, patients with Proteus syndrome have benefited from surgery and physical therapy.


Fish Odor Syndrome

Rotting Fish Next time you smell the sudden stench of rotting fish try not to be so quick to judge because it may be coming from a person with a rare medical condition. Trimethylaminuria, also known as Fish odor syndrome, happens when a body can’t break down certain nitrogen-containing compounds. This then results in a person having excessive body odor. Bad breath, offensive sweating, and smelly urine are also possible side effects.

Next time you smell the sudden stench of rotting fish, try not to be so quick to judge. It may be coming from a person with a rare medical condition.

Trimethylaminuria, also known as fish odor syndrome, happens when a body can’t break down certain nitrogen-containing compounds. This results in a person having excessive body odor. Bad breath, offensive sweating, and smelly urine are other possible side effects.



Neverous systemhttps://rarediseases.info.nih.gov/diseases/3006/congenital-insensitivity-to-pain-with-anhidrosis

CIPA, also known as congenital insensitivity to pain with anhidrosis, is a rare autosomal recessive disorder. Autosomal recessive disorders occur when a person inherits two mutated genes from their parents.

CIPA attacks the nervous system and prevents the body from sweating, feeling different types of pain, and sensing temperatures.

While there is no cure at this time, CIPA patients find regulating their body temperature to be an effective treatment.


Fatal Familial Insomnia


If you are searching the web in hopes of a self-diagnosis for your lack of sleep, you may have already stumbled upon fatal familial insomnia. The rare genetic brain disorder is defined by the inability to sleep.

Researchers have discovered that the disorder could potentially worsen over time if it isn’t treated properly. Fatal familial insomnia could also eventually lead to mental deterioration.

Sadly, there is currently no cure for this rare medical condition. 


Auto-brewery Syndrome


As crazy as it may sound, there is a disease that causes your body to naturally produce intoxicating quantities of ethanol. This leads a person to feel extremely tired, achy, and bloated.

The rare auto-brewery syndrome can be treated by reducing carbohydrates in your diet. Doctors have also been known to prescribe patients antifungal medications, which helps to stop the production of endogenous fermentation within a patient’s digestive system.

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