The signs and symptoms associated with myocarditis are varied, and relate either to the actual inflammation of the myocardium or to the weakness of the heart muscle that is secondary to the inflammation. Signs and symptoms of myocarditis include the following:

- Chest pain (often described as "stabbing" in character)

- Congestive heart failure (leading to swelling, shortness of breath and liver congestion)

- Palpitations (due to abnormal heart rhythms)

- Sudden death (in young adults, myocarditis causes up to 20% of all cases of sudden death)

- Fever (especially when infectious, e.g. in rheumatic fever)

- Symptoms in young children tend to be more nonspecific, with generalized malaise, poor appetite, abdominal pain, and chronic cough. Later stages of the illness will present with respiratory symptoms with increased work of breathing, and is often mistaken for asthma.

Since myocarditis is often due to a viral illness, many patients give a history of symptoms consistent with a recent viral infection, including fever, rash, diarrhea, joint pains, and easily becoming tired.

Myocarditis is often associated with pericarditis, and many people with myocarditis present with signs and symptoms that suggest myocarditis and pericarditis at the same time.

Among the signs of subacute bacterial endocarditis are:

- Malaise

- Weakness

- Excessive sweat

- Fever

Myocarditis, also known as inflammatory cardiomyopathy, is inflammation of the heart muscle. Symptoms can include shortness of breath, chest pain, decreased ability to exercise, and an irregular heartbeat. The duration of problems can vary from hours to months. Complications may include heart failure due to dilated cardiomyopathy or cardiac arrest.

Myocarditis is most often due to a viral infection. Other causes include bacterial infections, certain medications, toxins, and autoimmune disorders. A diagnosis may be supported by an electrocardiogram (ECG), increased troponin, heart MRI, and occasionally a heart biopsy. An ultrasound of the heart is important to rule out other potential causes such as heart valve problems.

Treatment depends on both the severity and the cause. Medications such as ACE inhibitors, beta blockers, and diuretics are often used. A period of no exercise is typically recommended during recovery. Corticosteroids or intravenous immunoglobulin (IVIG) may be useful in certain cases. In severe cases an implantable cardiac defibrillator or heart transplant may be recommended.

In 2013, about 1.5 million cases of acute myocarditis occurred. While people of all ages are affected, the young are most often affected. It is slightly more common in males than females. Most cases are mild. In 2015 cardiomyopathy, including myocarditis, resulted in 354,000 deaths up from 294,000 in 1990. The initial descriptions of the condition are from the mid-1800s.

Carditis is the inflammation of the heart or its surroundings. The plural of carditis is carditides.

It is usually studied and treated by specifying it as:

- Pericarditis is the inflammation of the pericardium

- Myocarditis is the inflammation of the heart muscle

- Endocarditis is the inflammation of the endocardium

- Pancarditis is the inflammation of the entire heart: the epicardium, the myocardium and the endocardium

- Reflux carditis refers to a possible outcome of esophageal reflux (also known as GERD), and involves inflammation of the esophagus/stomach mucosa

The signs and symptoms of Lemierre's syndrome vary, but usually start with a sore throat, fever, and general body weakness. These are followed by extreme lethargy, spiked fevers, rigors, swollen cervical lymph nodes, and a swollen, tender or painful neck. Often there is abdominal pain, diarrhea, nausea and vomiting during this phase. These signs and symptoms usually occur several days to 2 weeks after the initial symptoms.

Symptoms of pulmonary involvement can be shortness of breath, cough and painful breathing (pleuritic chest pain). Rarely, blood is coughed up. Painful or inflamed joints can occur when the joints are involved.

Septic shock can also arise. This presents with low blood pressure, increased heart rate, decreased urine output and an increased rate of breathing. Some cases will also present with meningitis, which will typically manifest as neck stiffness, headache and sensitivity of the eyes to light.

Liver enlargement and spleen enlargement can be found, but are not always associated with liver or spleen abscesses.

Other signs and symptoms that may occur:

- Headache (unrelated to meningitis)

- Memory loss

- Muscle pain

- Jaundice

- Decreased ability to open the jaw

- Crepitations are sometimes heard over the lungs

- Pericardial friction rubs as a sign of pericarditis (rare)

- Cranial nerve paralysis and Horner's syndrome (both rare)

Subacute bacterial endocarditis (also called endocarditis lenta) is a type of endocarditis (more specifically, infective endocarditis). Subacute bacterial endocarditis can be considered a form of type III hypersensitivity.

Myopericarditis is a combination of both myocarditis and pericarditis appearing in a single individual, namely inflammation of both the pericardium and the heart muscle. It can involve the presence of fluid in the heart. Myopericarditis refers primarily to a pericarditis with lesser myocarditis, as opposed to a perimyocarditis, though the two terms are often used interchangeably. Both will be reflected on an ECG. Myo-pericarditis usually involves inflammation of the pericardium, or the sac covering the heart.

The ACAM2000 smallpox vaccine has been known to cause myopericarditis in some people.

Lemierre's syndrome (or Lemierre's disease, also known as postanginal shock including sepsis and human necrobacillosis) refers to infectious thrombophlebitis of the internal jugular vein. It most often develops as a complication of a bacterial sore throat infection in young, otherwise healthy adults. The thrombophlebitis is a serious condition and may lead to further systemic complications such as bacteria in the blood or septic emboli.

Lemierre's syndrome occurs most often when a bacterial (e.g., "Fusobacterium necrophorum") throat infection progresses to the formation of a peritonsillar abscess. Deep in the abscess, anaerobic bacteria can flourish. When the abscess wall ruptures internally, the drainage carrying bacteria seeps through the soft tissue and infects the nearby structures. Spread of infection to the nearby internal jugular vein provides a gateway for the spread of bacteria through the bloodstream. The inflammation surrounding the vein and compression of the vein may lead to blood clot formation. Pieces of the potentially infected clot can break off and travel through the right heart into the lungs as emboli, blocking branches of the pulmonary artery that carry blood with little oxygen from the right side of the heart to the lungs.

Sepsis following a throat infection was described by Schottmuller in 1918. However, it was André Lemierre, in 1936, who published a series of 20 cases where throat infections were followed by identified anaerobic sepsis, of whom 18 patients died.

These depend on the amount of inflammation. These are covered in their relevant articles.

- Acute: Heart failure; pericardial effusion; etc.

- Chronic: Valve diseases as noted above; Reduced cardiac output; Exercise intolerance.

In addition to symptoms related to the provoking cause, sepsis is frequently associated with either fever, low body temperature, rapid breathing, elevated heart rate, confusion, and edema. Early signs are a rapid heart rate, decreased urination, and high blood sugar. Signs of established sepsis include confusion, metabolic acidosis (which may be accompanied by faster breathing and lead to a respiratory alkalosis), low blood pressure due to decreased systemic vascular resistance, higher cardiac output, and dysfunctions of blood coagulation (where clotting may lead to organ failure).

The drop in blood pressure seen in sepsis may lead to shock. This may result in light-headedness. Bruising or intense bleeding may occur.

Autoimmune heart diseases are the effects of the body's own immune defense system mistaking cardiac antigens as foreign and attacking them leading to inflammation of the heart as a whole, or in parts. The commonest form of autoimmune heart disease is rheumatic heart disease or rheumatic fever.

Sepsis is a life-threatening condition that arises when the body's response to infection causes injury to its own tissues and organs. Common signs and symptoms include fever, increased heart rate, increased breathing rate, and confusion. There also may be symptoms related to a specific infection, such as a cough with pneumonia, or painful urination with a kidney infection. In the very young, old, and people with a weakened immune system, there may be no symptoms of a specific infection and the body temperature may be low or normal, rather than high. Severe sepsis is sepsis causing poor organ function or insufficient blood flow. Insufficient blood flow may be evident by low blood pressure, high blood lactate, or low urine output. Septic shock is low blood pressure due to sepsis that does not improve after reasonable amounts of intravenous fluids are given.

Sepsis is caused by an immune response triggered by an infection. Most commonly, the infection is bacterial, but it may also be from fungi, viruses, or parasites. Common locations for the primary infection include lungs, brain, urinary tract, skin, and abdominal organs. Risk factors include young or old age, a weakened immune system from conditions such as cancer or diabetes, major trauma, or burns. An older method of diagnosis was based on meeting at least two systemic inflammatory response syndrome (SIRS) criteria due to a presumed infection. In 2016, SIRS was replaced with qSOFA which is two of the following three: increased breathing rate, change in level of consciousness, and low blood pressure. Blood cultures are recommended preferably before antibiotics are started, however, infection of the blood is not required for the diagnosis. Medical imaging should be used to look for the possible location of infection. Other potential causes of similar signs and symptoms include anaphylaxis, adrenal insufficiency, low blood volume, heart failure, and pulmonary embolism, among others.

Sepsis usually is treated with intravenous fluids and antibiotics. Typically, antibiotics are given as soon as possible. Often, ongoing care is performed in an intensive care unit. If fluid replacement is not enough to maintain blood pressure, medications that raise blood pressure may be used. Mechanical ventilation and dialysis may be needed to support the function of the lungs and kidneys, respectively. To guide treatment, a central venous catheter and an arterial catheter may be placed for access to the bloodstream. Other measurements such as cardiac output and superior vena cava oxygen saturation may be used. People with sepsis need preventive measures for deep vein thrombosis, stress ulcers and pressure ulcers, unless other conditions prevent such interventions. Some might benefit from tight control of blood sugar levels with insulin. The use of corticosteroids is controversial. Activated drotrecogin alfa, originally marketed for severe sepsis, has not been found to be helpful, and was withdrawn from sale in 2011.

Disease severity partly determines the outcome. The risk of death from sepsis is as high as 30%, from severe sepsis as high as 50%, and from septic shock as high as 80%. The number of cases worldwide is unknown as there is little data from the developing world. Estimates suggest sepsis affects millions of people a year. In the developed world approximately 0.2 to 3 people per 1000 are affected by sepsis yearly, resulting in about a million cases per year in the United States. Rates of disease have been increasing. Sepsis is more common among males than females. The medical condition has been described since the time of Hippocrates. Septicemia and blood poisoning are terms that referred to the microorganisms or their toxins in the blood and are no longer commonly used.

Septic arthritis, also known as joint infection or infectious arthritis, is the invasion of a joint by an infectious agent resulting in joint inflammation. Symptoms typically include redness, heat, and pain in a single joint associated with a decreased ability to move the joint. Onset is usually rapid. Other symptoms may include fever, weakness, and headache. Occasionally more than one joint may be involved.

Causes include bacteria, viruses, fungi, and parasites. Risk factors include an artificial joint, prior arthritis, diabetes, and poor immune function. Most commonly joints becomes infected via the blood but may also become infected via trauma or an infection around the joint. Diagnosis is generally based on aspirating joint fluid and culturing it. White blood cells of greater than 50,000 mm or lactate greater than 10 mmol/l in the joint fluid also makes the diagnosis likely.

Initial treatment typically include antibiotics such as vancomycin, ceftriaxone, or ceftazidime. Surgery may also be done to clean out the joint. Without early treatment long term joint problems may occur. Septic arthritis occurs in about 5 people per 100,000 each year. It occurs more commonly in older people. With treatment about 15% of people die while without 66% die.

Symptoms in eosinophilc myocarditis are highly variable. They tend to reflect the many underlying disorders causing eosinophil dysfunction as well as the widely differing progression rates of cardiac damage. Before cardiac symptoms are detected, some 66% of cases have symptoms of a common cold and 33% have symptoms of asthma, rhinitis, urticarial, or other allergic disorder. Cardiac manifestations of eosinophilic myocarditis range from none to life-threatening conditions such as cardiogenic shock or sudden death due to abnormal heart rhythms. More commonly the presenting cardiac symptoms of the disorder are the same as those seen in other forms of heart disease: chest pain, shortness of breath, fatigue, chest palpitations, light headedness, and syncope. In its most extreme form, however, eosinophilic myocarditis can present as acute necrotizing eosinophilic myocarditis, i.e. with symptoms of chaotic and potentially lethal heart failure and heart arrhythmias. This rarest form of the disorder reflects a rapidly progressive and extensive eosinophilic infiltration of the heart that is accompanied by massive myocardial cell necrosis.

Hypereosinophilia (i.e. blood eosinophil counts at or above 1,500 per microliter) or, less commonly, eosinophilia (counts above 500 but below 1,500 per microliter) are found in the vast majority of cases of eosinophilic myocarditis and are valuable clues that point to this rather than other types of myocarditis or myocardial injuries. However, elevated blood eosinophil counts may not occur during the early phase of the disorder. Other, less specific laboratory findings implicate a cardiac disorder but not necessarily eosinophilic myocarditis. These include elevations in blood markers for systemic inflammation (e.g. C reactive protein, erythrocyte sedimentation rate), elevations in blood markers for cardiac injury (e.g. creatine kinase, troponins); and abnormal electrocardiograms ( mostly ST segment-T wave abnormalities).

Signs and symptoms usually include a fever greater than , chills, low abdominal pain, and possibly bad smelling vaginal discharge.

Eosinophilic coronary periarteritis is a heart disorder caused by extensive eosinophilic infiltration of the adventitia and periadventitia, i.e. the soft tissues, surrounding the coronary arteries. The intima, tunica media, and tunica intima layers of these arteries remain intact and are generally unaffected. Thus, this disorder is characterized by episodes of angina, particularly Prinzmetal's angina, and sudden death due to heart dysfunction. The disorder is considered distinct from eosinophilic myocarditis.

Septic shock is a serious medical condition that occurs when sepsis, which is organ injury or damage in response to infection, leads to dangerously low blood pressure and abnormalities in cellular metabolism.

The primary infection is most commonly caused by bacteria, but also may be by fungi, viruses or parasites. It may be located in any part of the body, but most commonly in the lungs, brain, urinary tract, skin or abdominal organs. It can cause multiple organ dysfunction syndrome (formerly known as multiple organ failure) and death.

Frequently, people with septic shock are cared for in intensive care units. It most commonly affects children, immunocompromised individuals, and the elderly, as their immune systems cannot deal with infection so effectively as those of healthy adults. The mortality rate from septic shock is approximately 25–50%.

Septic arthritis most commonly causes pain, swelling, and warmth at the affected joint. Therefore, those affected by septic arthritis will often refuse to use the extremity and prefer to hold the joint rigidly. Fever is also a symptom; however, it is less likely in older patients.

The most common joint affected is the knee. Hip, shoulder, wrist, or elbow joints are less commonly affected. Spine, sternoclavicular, and sacroiliac joints can also be involved; however, the most common cause of arthritis in these joints is intravenous drug use.

Usually only one joint is effected. More than one joint can be involved if bacteria are seeded through the bloodstream.

Septic shock is a subclass of distributive shock, a condition in which abnormal distribution of blood flow in the smallest blood vessels results in inadequate blood supply to the body tissues, resulting in ischemia and organ dysfunction. Septic shock refers specifically to distributive shock due to sepsis as a result of infection.

Septic shock may be defined as sepsis-induced low blood pressure that persists despite treatment with intravenous fluids. Low blood pressure reduces tissue perfusion pressure, causing the tissue hypoxia that is characteristic of shock. Cytokines released in a large scale inflammatory response result in massive vasodilation, increased capillary permeability, decreased systemic vascular resistance, and low blood pressure. Finally, in an attempt to offset decreased blood pressure, ventricular dilatation and myocardial dysfunction occur.

Septic shock may be regarded as a stage of SIRS (Systemic Inflammatory Response Syndrome), in which sepsis, severe sepsis and multiple organ dysfunction syndrome (MODS) represent different stages of a pathophysiological process. If an organism cannot cope with an infection, it may lead to a systemic response - sepsis, which may further progress to severe sepsis, septic shock, organ failure, and eventually, result in death.

After childbirth a woman's genital tract has a large bare surface, which is prone to infection. Infection may be limited to the cavity and wall of her uterus, or it may spread beyond to cause septicaemia (blood poisoning) or other illnesses, especially when her resistance has been lowered by a long labour or severe bleeding. Puerperal infection is most common on the raw surface of the interior of the uterus after separation of the placenta (afterbirth); but pathogenic organisms may also affect lacerations of any part of the genital tract. By whatever portal, they can invade the bloodstream and lymph system to cause septicemia, cellulitis (inflammation of connective tissue), and pelvic or generalized peritonitis (inflammation of the abdominal lining). The severity of the illness depends on the virulence of the infecting organism, the resistance of the invaded tissues, and the general health of the woman. Organisms commonly producing this infection are "Streptococcus pyogenes"; staphylococci (inhabitants of the skin and of pimples, carbuncles, and many other pustular eruptions); the anaerobic streptococci, which flourish in devitalized tissues such as may be present after long and injurious labour and unskilled instrumental delivery; "Escherichia coli" and "Clostridium perfringens" (inhabitants of the lower bowel); and "Clostridium tetani".

SIRS is frequently complicated by failure of one or more organs or organ systems. The complications of SIRS include:

- Acute lung injury

- Acute kidney injury

- Shock

- Multiple organ dysfunction syndrome

The causes of SIRS are broadly classified as infectious or noninfectious. Causes of SIRS include:

- trauma

- burns

- pancreatitis

- ischemia

- hemorrhage

Other causes include:

- Complications of surgery

- Adrenal insufficiency

- Pulmonary embolism

- Complicated aortic aneurysm

- Cardiac tamponade

- Anaphylaxis

- Drug overdose

Idiopathic giant-cell myocarditis (IGCM) is a cardiovascular disease of the muscle of the heart (myocardium).

The condition is rare; however, it is often fatal and there is no proven cure because of the unknown nature of the disorder.

IGCM frequently leads to death with a high rate of about 70% in first year. A patient with IGCM typically presents with symptoms of heart failure, although some may present initially with ventricular arrhythmia or heart block. Median age from the time the disease is diagnosed to the time of death is approximately 6 months. 90% of patients are either deceased by the end of 1 year or have received a heart transplant. Diagnosis is made by endomyocardial biopsy during heart catheterization. Biopsy shows multinucleated giant cells and thus the name. While previously cases universally required heart transplantation, recent studies show that two thirds of patients can survive past one year with high doses of immunosuppressants such as prednisone and cyclosporine. The transplanted heart has a high chance of disease recurrence. Compared to lymphocytic (presumed viral) myocarditis, giant cell myocarditis is much more severe with much more rapid progression.

It is suggested to be caused by T-lymphocytes.

An infectious intracranial aneurysm (IIA, also called mycotic aneurysm) is a cerebral aneurysm that is caused by infection of the cerebral arterial wall.

Pain or tenderness to palpation usually occurs on the sides of the sternum, affects multiple ribs, and is often worsened with coughing, deep breathing, or physical activity. On physical examination, a physician inspects and feels the patient for swollen or tender areas, and can often produce the pain of costochondritis by moving the patient's rib cage or arms.

A factor that may aid in the differentiation of costochondritis from Tietze syndrome is the location of the pain on the sternum. Costochondritis typically affects the third, fourth, and fifth costosternal joints in contrast to Tietze's syndrome, which usually affects the second or third costosternal joint. Pain from costochondritis typically resolves within one year.