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Things You Think Are Contagious—But Aren’t

Understanding what is and isn’t contagious is vital in maintaining our health and well-being. We often make assumptions based on myths, hearsay, or partial information, leading to misconceptions about various conditions and how they’re transmitted. This article dissects and debunks some common beliefs about things you think are contagious but, surprisingly, aren’t. With accurate information, we can better navigate our world, make informed decisions, and perhaps even alleviate unnecessary fears.

Colds Only Through Air

Have you ever heard someone blame the cold weather for their sniffling and sneezing? It’s a common belief that exposure to cold weather or going outside with wet hair can result in catching a cold. However, this is not the case. Colds are caused by viruses, primarily rhinoviruses, which we catch from other infected individuals—not the temperature of our environment.

The misconception likely arises from the fact that we tend to catch more colds during the winter season. This correlation, however, is due to people spending more time indoors in close proximity, thus increasing the likelihood of the virus spreading. Furthermore, the lower humidity in winter can dry out our nasal passages, making them more susceptible to viral infection. So, the next time you forget your hat on a chilly day, don’t fret about catching a cold!

Poison Ivy/Oak

Poison ivy and poison oak are infamous for the itchy, blistering rash they cause upon contact. Many people believe this rash can spread from person to person or even from blisters to other parts of the body. In reality, this is not true. The cause of the rash is an oil called urushiol, found in the leaves, stems, and roots of these plants.

When this oil comes into contact with the skin, it triggers an allergic reaction in susceptible individuals, leading to a rash. However, once the oil is washed off, the rash itself is not contagious. It might appear to spread over a few days, but that’s due to the skin reacting at different rates or the oil lingering on clothes, pets, or gardening tools—not because the rash is “spreading”. It’s important to wash all clothes and items that might have been in contact with the plant to prevent re-exposure.


Warts, those small, rough-textured growths that can appear anywhere on the skin, are often believed to be easily spread by casual contact. While it is true that the human papillomavirus (HPV) causes warts, simply touching a wart on someone else does not guarantee you will get one. The HPV strains that cause skin warts are usually transmitted through breaks in the skin, and even then, not everyone exposed to them will develop warts.

That said, indirect transmission is possible. Shared environments such as communal showers or pool decks can facilitate transmission, especially if you have cuts or abrasions. So, while you might want to avoid touching someone else’s wart, it’s not nearly as contagious as you might think. Maintaining good hygiene practices is usually enough to prevent the spread of warts.

Grey Hair

Have you ever plucked a grey hair, fearing that more will sprout in its place, as the myth suggests? Contrary to this widespread belief, grey hair is not contagious, nor does it multiply if you pluck one. The color of our hair is determined by pigments produced by cells in the hair follicles known as melanocytes. As we age, these cells may gradually stop producing pigment, leading to the hair turning grey or white.

Plucking one grey hair will not cause more to appear. When a hair is plucked, it will regrow from the same follicle—if that follicle has stopped producing pigment, the new hair will be grey as well. However, the hair follicles around it remain unaffected. So next time you spot a silver strand, don’t worry about it triggering an avalanche of grey.


Cavities are another common health issue surrounded by misconceptions. While it’s true that bacteria involved in the formation of cavities can be transferred from one person to another through saliva, it’s not the bacteria alone that cause cavities. Poor dental hygiene, dietary habits, and genetic predisposition play significant roles in whether or not a person develops cavities.

Cavity-causing bacteria, namely Streptococcus mutans, can thrive when we frequently consume foods high in sugar and starch and fail to clean our teeth properly. If these conditions aren’t met, you may not develop a cavity even if the bacteria are present in your mouth. Thus, instead of avoiding your loved ones’ kisses, maintaining good oral hygiene and a balanced diet can prevent cavities more effectively.


Obesity, a serious health issue affecting millions globally, is often misinterpreted as “contagious”. The concept of ‘social contagion’ in obesity stems from the idea that habits, attitudes, and behaviors can spread through social networks. However, this doesn’t mean that obesity itself is contagious in the same way an infection might be.

Individuals who live in the same household or share a close relationship may adopt similar eating habits and activity levels, potentially leading to weight gain. However, many factors, including genetics, metabolism, lifestyle choices, and socioeconomic status, play a role in obesity. While the habits of those around us can influence us, obesity is not ‘caught’ by another person, like a cold or a flu.


Cancer, one of the leading causes of death globally, is a topic that often evokes fear and uncertainty. Some people worry that they can “catch” cancer from someone else. Rest assured, cancer is not a contagious disease. It cannot be transmitted from person to person through any form of contact.

Cancer develops due to changes (mutations) in our genes that control how our cells function, especially how they grow and divide. These changes can occur due to various factors, including genetic inheritance, exposure to certain environmental factors, lifestyle choices such as smoking or poor diet, and even random chance. Understanding the true causes of cancer can help alleviate unnecessary fears and focus our energy on proven prevention strategies.

Mental Illness

Mental illnesses, such as depression, anxiety disorders, or schizophrenia, are often misunderstood, and it’s not uncommon for people to mistakenly believe they can be “caught” by others. While mental health disorders can feel isolating and burdensome, they are not contagious in the traditional sense. You can’t catch depression from a friend or develop an anxiety disorder from a coworker.

These conditions are complex and are believed to result from a combination of genetic, biological, environmental, and psychological factors. Stress or trauma can trigger symptoms in people already predisposed to these conditions. Social support, therapy, and sometimes medication can all play a crucial role in managing mental illness, but it’s essential to remember these conditions are not transmitted from person to person like a virus or bacteria.


The myths surrounding acne can be as persistent as the condition itself. One such belief is that acne is contagious. However, this is not the case. Acne develops when pores in the skin become clogged with dead skin cells and oil. Certain bacteria that live on the skin, known as Propionibacterium acnes, can then proliferate and cause inflammation and acne.

While it’s true that the bacteria associated with acne can be transferred from person to person, simply having the bacteria on your skin doesn’t guarantee that you will develop acne. Genetic factors, hormonal changes, stress, and certain medications play a significant role in acne development. So, even if you share a hat or a headset with someone with acne, rest assured you won’t ‘catch’ their acne.

Genes And Genetic Disorders

One of the most commonly misunderstood aspects of health and disease is the role of genetics. People often express concerns about “catching” a genetic disorder from a friend or partner, but this is not how genetics works. Genetic disorders are caused by mutations or changes in a person’s DNA and can only be inherited from parents—not contracted from others.

For example, conditions like cystic fibrosis or Huntington’s disease are inherited when a person receives a specific mutated gene from one or both parents. They can’t be passed on through casual or even intimate contact. While it’s important to understand our genetic risks, it’s equally crucial to realize we can’t ‘catch’ genetic disorders from others in our day-to-day lives.

Dispelling Myths and Promoting Health Awareness

It’s clear that knowledge is indeed power. By debunking these myths about things we often mistakenly think are contagious, we’ve learned how these conditions truly spread or develop. This understanding not only helps us to dispel unnecessary fears but also guides us to take appropriate actions for prevention or management. Remember, always consult with a healthcare professional to get accurate and personalized advice when in doubt. Let’s continue to promote health literacy and awareness in our journey towards healthier lives.