Illness

With the infamous guinea pig disease now a thing of The Sims past, Sims can now catch a few different diseases, each with their own symptoms and method of catching - some are contagious, too.

Guinea Pig Disease
Guinea Pig Disease is introduced in Livin' Large. Sims can catch it if they are bitten by a guinea pig that has a dirty cage, or from other Sims who have been infected with the disease. Objects cloned from the guinea pig can also cause this disease. Sims infected with Guinea Pig Disease will sneeze and cough frequently, and their Comfort and Energy motives will rapidly decline. An infected Sim will die if not treated within time.

Due to a glitch, a Sim who dies from Guinea Pig Disease cannot be successfully resurrected by the Grim Reaper. Once they are restored to life they will immediately die again.

Each instance of Guinea Pig Disease is restricted to the lot the Sim was infected on, so an infected Sim will not display symptoms, be infectious, or die outside of the lot on which they caught the disease. Therefore, a Sim with the disease can safely go to a community lot or be invited to another Sim's house as a visitor. It is possible for a Sim to be infected on multiple lots, however.

Treatment

 * 1) Keep the infected Sim home from work or school and try to keep their Comfort and Energy motives up.
 * 2) Purchasing The Forgotten Guinea Pig painting will clear the disease from the household after 16 Sim hours.
 * 3) A Sim who drinks a white potion created with The "Concoctanation Station" chemistry set will be immediately cured of the disease. Additionally drinking a blue potion will restore three random motives which, while not directly curing the disease, can help them to recover from it.

Montezuma's Revenge
Montezuma's Revenge, also known as "Poopy Pants" (the name used by Maxis in the code), is a disease introduced in Vacation. It's a form of food poisoning, and Sims can get it from eating at buffet tables when their Hygiene is low. Montezuma's Revenge cannot kill a Sim, but will cause great discomfort to the ill Sim as the Bladder motive will rapidly decline, making them spend plenty of time in the bathroom.

Treatment
The disease is not deadly, and will go away on its own after a period of time. Try to keep the affected Sim's Bladder motive up.

Unleashed Mystery Illness
Reportedly introduced in Unleashed, this was dubbed the "Mystery Illness" because its exact nature and origin was unknown. Its existence was inferred, but never officially acknowledged or confirmed, and reports of it spread around the Sims community. Reported symptoms are those of the Guinea Pig Disease, but it does not require the presence of a guinea pig. It could reportedly affect both humans and pets, and reported symptoms in pets include listlessness and an inability to maintain the Hunger motive.

It does not appear to exist as a separate entity, but may have been the result of a bug involving existing illnesses. What it is, and whether it exists at all, remains subject to dispute. Investigations have shown that there is no reference to disease in any of the files that come with Unleashed (see this thread at Simblesse Oblige), and that code which claims to cure the disease refers to a disease controller file which was included in Vacation, which actually contains code for Poopy Pants.

Nervous Breakdown
Nervous Breakdowns are introduced in Superstar If a famous Sim has repeated failures in Studio Town the Sim will enter a catatonic state and lose Comfort, Fun, Bladder and potentially star power. Subsequently the Sim's breakdown will be reported in the tabloid.

Symptoms

 * Coughing – Causes a drop in comfort.
 * Sneezing – Causes a drop in comfort.
 * Nausea – Causes a drop in comfort.
 * Vomiting – Causes a drop in comfort. Affected Sim will run to a toilet, or vomit on the floor if they can't find one.
 * Diarrhea – Causes a drop in bladder.
 * Fatigue – Causes a drop in energy.

Contagiousness
Food poisoning and morning sickness cannot be passed between Sims. All other diseases can, to varying degrees. Mysterious disease is more contagious than flu, which is more contagious than a cold, which is more contagious than pneumonia.

Fatality
If certain illnesses are not cured within ten days, the Sim will die from illness. A tombstone above the Sim's head indicates the Sim is near death from illness. Children are taken away by a Social Worker before they get a chance to die. Toddlers and babies cannot get ill. The mysterious disease can kill a Sim of any age group in less than 24 Sim hours, so it's possible for a child to die of the mysterious disease.

Call in sick
This interaction is available by calling work on the phone, and allows a Sim to miss work without fear of being fired. It becomes available one hour before the carpool arrives, and remains available until the Sim is one hour late. If the Sim is not actually sick, its success depends on job performance. It will always succeed if the Sim is actually ill.

Morning Sickness
Morning sickness almost always happens when a Sim is pregnant and in the first trimester. It also has the same symptoms as food poisoning. If the Sim is a female and didn't plan for a baby, or if it's a male Sim and wasn't recently abducted, then it is most likely they just ate some spoiled food.
 * Symptoms – Vomiting, nausea
 * Fatal? – No
 * Contagious – No

The only way guaranteed to prevent a Sim from getting morning sickness is to download a mod that will stop it from happening. Otherwise its intensity varies from Sim to Sim.

Food Poisoning
There is a 5% chance any time a Sim eats spoiled or burned food that the Sim will get food poisoning. This can occur if food spoils while a Sim is eating it, or if sloppy Sims eat out of the rubbish bin.
 * Symptoms – Vomiting, nausea
 * Fatal? – Yes
 * Contagious – No

Cold
There is a 1% chance any time a Sim goes to work or school that the Sim will catch a cold. Infected Sims will suffer from coughing and sneezing fits, causing drops in comfort.
 * Symptoms – Coughing, sneezing
 * Fatal? – No, but will become pneumonia if not cured within ten days
 * Contagious – Highly

Pneumonia
If the cold is not cured within ten days it will turn into pneumonia. The pneumonia has all the symptoms of both the cold and the flu, as well as sharp and sudden drops in Energy in which a Sim appears to nearly pass out. If energy drops low enough, the Sim will pass out. Sims with pneumonia may die if not treated.
 * Symptoms – Coughing, fatigue, purple smoke (out of their heads)
 * Fatal? – Yes
 * Contagious – Slightly

Flu
If a Sim goes near cockroaches, there is a 5% chance they will catch the flu. The flu has all the symptoms of a cold with sharp drops in fun and energy as well. Evil witches are immune to the disease spread by cockroaches.
 * Symptoms – Coughing, diarrhea
 * Fatal? – Yes
 * Contagious – Highly

When the Beaker household in Strangetown is first played, there will be cockroaches near the refrigerator. Both Loki and Nervous will go to stomp on them and are likely to catch the flu. It is best to cancel out this action before they get there, and call an exterminator.

Mysterious Disease
Also known as "Virus", Sims can be infected with this when using the biotech station with low logic skill. It should be noted that this disease is highly contagious and can easily spread through the entire neighborhood in a matter of days.
 * Symptoms – Two random symptoms.
 * Fatal? – Yes
 * Contagious – Extremely

Rest
The best cure for all illnesses is rest. Keep the sick Sim away from healthy Sims, and keep their comfort and energy up by making them sleep and relax on the bed, until a message appears saying they are cured. If the Sim is able to meditate, this will also help.

Medicine
The medicine made with the biotech station cuts down the resting time needed to be cured of a sickness. Players who do not have either FreeTime (with up-to-date patches) or Apartment Life will need to get a mod from More Awesome Than You! for the medicine to work properly.

Orange Juice
If The Sims 2: Seasons is installed, drinking orange juice made from Tasty or Mouthwatering fruit will cure colds, or at least reduce the amount of time a Sim will need to rest.

Grandma's Comfort Soup
With The Sims 2: FreeTime installed, Sims with Family as their primary or secondary aspiration can achieve the aspiration benefit Grandma's Comfort Soup. When eaten, it will cure any disease a Sim has. It is recommended to have at least one Family Sim in the household just in case any Sim has caught any illness. Sims can also add Grandma's Comfort Soup to the menu in an owned restaurant so they can cure any customers that happen to be ill. This can be done even if the chef does not have this aspiration benefit.

Nausea
Nausea is a common illness Sims could have. Sims will get the "Nauseous" moodlet that will last for 2 hours, and after the moodlet expires, the Sims will throw up. Being nauseous isn't contagious nor fatal, and will go away after they vomit. Below is several ways to get nauseous.


 * Morning Sickness
 * Morning sickness will always happen when a Sim is pregnant and in the first trimester. Sims will randomly get the "Nauseous" moodlet and eventually they will vomit. Shortly after vomiting, the Sim will once again become nauseous


 * Food Poisoning
 * If Sims eat spoiled or burned food there is a slight chance they will receive the "Nauseous" moodlet.


 * Visceroidal Nausea/Tiberium Poisoning
 * Keeping Tiberium, a radioactive rock, in a Sim's inventory for a while will give them "Visceroidal Nausea" moodlet, which is similar to the normal "Nauseous" moodlet.


 * Eating Meat
 * If a Vegetarian eats meat, they will receive the Nauseous moodlet and will vomit after a while. It also happens to Vegetarian vampires who drink from Sims.


 * Consuming Plasma
 * When a normal Sim drinks Plasma or eats any products containing plasma, such as nectar, they will become Nauseous.


 * Floor Hygienator Temporary Malfunction
 * When a floor hygienator isn't created by Sims that have completed the Master Inventor skill challenge, it will have a temporary malfunction that causes it to backfire to the Sims, causing them to get nauseous.


 * Experimental Treatment
 * Sims who work in Medical career can try an experimental treatment on themselves or other Sims. One of the possible outcome of the treatment will cause Sims to pass out or get nauseous.


 * Alchemy Failure
 * While attempting to mix an alchemical elixir, a Sim may occasionally fail and receive the Nauseous moodlet instead.


 * Herb Nausea
 * Consuming or burning herbs can sometimes cause Sims to get nauseous and make them vomit when the timer runs out. If the Sims with herb nausea eat another herb before timer runs out, they will vomit instantly.

Food Poisoning
As stated before, eating spoiled or burnt food may cause Sims to get nauseous. There's a 15% chance that eating from a food truck will give Sims the "Food Poisoning" moodlet. Snob Sims have 30% chance of getting food poisoning from the food truck.

Mummy's Curse
If a Sim loses a fight with a Mummy, there's a chance they will get cursed. If the curse is not cured after two weeks, the Sim will die. Sims must go to the Sphinx and make a plea to enter the tomb inside the Sphinx. Then they have to explore to end of the tomb to get blessed with a Soulpeace Statue. The curse can also be cured by being kissed by a King Cobra (from the snake-charming basket).

Pestilence Curse
In The Sims 3: Supernatural, if a Sim is cursed with the Pestilence Curse by a witch and is not cured within 24 hours, they can get sick. It can be cured by casting a Sunlight Charm on the cursed Sim. The curse is contagious, so the Sim can affect other Sims whom they have had contact with.

Cold
In The Sims 3: Seasons, Sims can get colds, more likely in Fall. Players will be notified when their Sims get a cold, "(Sim Name) is starting to feel a bit ill". Sims who get a cold will have "Germy" moodlet that will last for 2 days. The Cold is contagious, so it is best to keep sick Sims away from healthy Sims. Sims can get health advice at the hospital or get a flu shot that will make them immune for a full-year for §200 each. The flu shot is only available in Fall and Winter.

Allergy
In The Sims 3: Seasons, Sims can get allergies from wildflowers, more likely in Spring. Sims get "Allergy Haze" moodlet when they get allergies, which lasts for up to 10 days. They can get an allergy shot at the hospital for §200. The allergy shot is only available in Spring. Allergies are genetic, and they may be passed down to the offspring.

The Sims Medieval
Unlike The Sims 3, The Sims Medieval offers both injury and disease. Death by plague is also present. Diseases will usually give Sims a bad moodlet and can be cured by visiting a Physician or by applying curative tonics and/or health salves. Every disease is contagious in this game.

Sickness
This is the first and the least serious form of a disease. It can easily be cured by applying Weak Curative Tonics, or by visiting a Physician. Gives a -10 moodlet.

Infection
If a sickness is not cured, then it will turn into an infection. Infections are usually cured by applying Moderate Curative Tonics (unlocked by Quest) or by visiting a Physician. Gives a -20 moodlet.

Disease
An infection will turn into a disease if cure is not met. This kind of disease is quite serious. It can easily be cured by applying Strong Curative Tonics or visiting a Physician. Gives a -30 moodlet.

Plague
In case a disease is not cured, it will turn into a plague. Plague can cause a Sim to die, so it has to be cured immediately. When a Sim has a plague, black smoke will appear above their head. A Plague can only be cured by visiting a Physician. It can also be reduced to an illness by a Wizard, using the spell Miasma. Mend will also completely remove it after using the spell Miasma to reduce it. Gives a -50 moodlet.

Minor Injury
This is the least serious form of injury. It can easily be healed either by applying Weak Health Salves or visiting a Physician. Gives a -10 moodlet.

Moderate Injury
When a minor injury is not healed, it will turn into a moderate injury. Moderate injuries can be healed by applying Moderate Health Salves (unlocked by Quest) or visiting a Physician. Gives a -20 moodlet.

Major Injury
The most serious form of injury. The Sim will be in bandages. It can easily be healed by applying Strong Health Salves or visiting a Physician. Gives a -30 moodlet.

The Sims 4
Illnesses are reintroduced in The Sims 4: Get to Work. Illnesses are as follows:
 * Rashes
 * Sweaty Shivers
 * Bloaty Head
 * Starry Eyes
 * Llama Flu
 * Gas and Giggles
 * Itchy Plumbob
 * Burning Belly
 * Triple Threat

Often, red marks on the skin signify an illness. A moodlet is also given.

None of these illnesses are major and are very easily cured. Sims can either drink some hot tea, take a nap or drink medicine purchased from a computer. Sims may not be able to visit the hospital (only unplayable sims visit the hospital), so home cures like the ones above can apply in healing your sim.

Trivia

 * If The Sims 3: Pets installed, Dogs also can get cold and get "Germy" moodlet that will last for 2 days. The Cold is also contagious, so it is best to keep sick Dogs away from healthy Sims and Dogs. Since Dogs are Pet, they cannot get a flu shot at hospital so they cannot be cured except waiting for the moodlet expire.