All Diseases

Radiation sickness is damage to your body caused by a large dose of radiation often received over a short period of time (acute). The amount of radiation absorbed by the body — the absorbed dose — determines how sick you'll be.

Radiation sickness is also called acute radiation sickness, acute radiation syndrome or radiation poisoning. Common exposures to low-dose radiation, such as X-ray or CT examinations, don't cause radiation sickness.

Although radiation sickness is serious and often fatal, it's rare. Since the atomic bombings of Hiroshima and Nagasaki, Japan, during World War II, most cases of radiation sickness have occurred after nuclear industrial accidents such as the 1986 fire that damaged the nuclear power plant at Chernobyl or the 2011 earthquake that damaged the nuclear power plant on the east coast of Japan.

Ramsay Hunt syndrome (herpes zoster oticus) occurs when a shingles infection affects the facial nerve near one of your ears. In addition to the painful shingles rash, Ramsay Hunt syndrome can cause facial paralysis and hearing loss in the affected ear.

Ramsay Hunt syndrome is caused by the same virus that causes chickenpox. After chickenpox heals, the virus lies dormant in your nerves. Years later, it may reactivate. If the virus reactivates and affects your facial nerve, the result is Ramsay Hunt syndrome.

Prompt treatment of Ramsay Hunt syndrome can reduce your risk of complications, which can include permanent facial muscle weakness and deafness.

Raynaud's (ray-NOHZ) disease causes some areas of your body — such as your fingers and toes — to feel numb and cold in response to cold temperatures or stress. In Raynaud's disease, smaller arteries that supply blood to your skin narrow, limiting blood circulation to affected areas (vasospasm).

Women are more likely than men to have Raynaud's disease, also known as Raynaud or Raynaud's phenomenon or syndrome. It appears to be more common in people who live in colder climates.

Treatment of Raynaud's disease depends on its severity and whether you have other health conditions. For most people, Raynaud's disease isn't disabling, but can affect quality of life.

Reactive arthritis is joint pain and swelling triggered by an infection in another part of your body — most often your intestines, genitals or urinary tract.

Your knees and the joints of your ankles and feet are the usual targets of reactive arthritis. Inflammation also may affect your eyes, skin and urethra when you have reactive arthritis.

Although reactive arthritis is sometimes called Reiter's syndrome, Reiter's is actually a specific type of reactive arthritis. In Reiter's, inflammation typically affects the eyes and urethra, as well as your joints.

Reactive arthritis isn't common. For most people, signs and symptoms of reactive arthritis come and go, eventually disappearing within 12 months.

Reactive attachment disorder is a rare but serious condition in which an infant or young child doesn't establish healthy attachments with parents or caregivers. Reactive attachment disorder may develop if the child's basic needs for comfort, affection and nurturing aren't met and loving, caring, stable attachments with others are not established.

With treatment, children with reactive attachment disorder may develop more stable and healthy relationships with caregivers and others. Treatments for reactive attachment disorder include positive child and caregiver interactions, a stable, nurturing environment, psychological counseling, and parent or caregiver education.

Rebound headaches (medication-overuse headaches) are caused by regular, long-term use of medication to treat headaches, such as migraine. Pain relievers offer relief for occasional headaches. But if you take them more than a couple of days a week, they may trigger rebound headaches.

It appears that any medication taken for pain relief can cause rebound headaches, but only if you already have a headache disorder. Pain relievers taken regularly for another condition, such as arthritis, have not been shown to cause rebound headaches in people who never had a headache disorder.

Rebound headaches usually stop when you stop taking the pain medication. It's tough in the short term, but your doctor can help you beat rebound headaches for long-term relief.

A rectovaginal fistula is an abnormal connection between the lower portion of your large intestine — your rectum — and your vagina. Contents of your bowel can leak through the fistula, meaning you might pass gas or stool through your vagina.

A rectovaginal fistula may result from an injury during childbirth, Crohn's disease or other inflammatory bowel disease, radiation treatment or cancer in the pelvic area, or a complication following surgery in the pelvic area.

The symptoms of a rectovaginal fistula often cause emotional distress as well as physical discomfort, which can impact self-esteem and intimate relationships. Though bringing up the subject with your doctor may be difficult, it's important to have a rectovaginal fistula evaluated. Some rectovaginal fistulas may close on their own, but most need to be repaired surgically.

Recurrent breast cancer is breast cancer that comes back after initial treatment. Although the initial treatment is aimed at eliminating all cancer cells, a few may have evaded treatment and survived. These undetected cancer cells multiply, becoming recurrent breast cancer.

Recurrent breast cancer may occur months or years after your initial treatment. The cancer may come back in the same place as the original cancer (local recurrence), or it may spread to other areas of your body (distant recurrence).

Learning you have recurrent breast cancer may be harder than dealing with the initial diagnosis. But having recurrent breast cancer is far from hopeless. Treatment may eliminate local, regional or distant recurrent breast cancer. Even if a cure isn't possible, treatment may control the disease for long periods of time.

Rapid eye movement (REM) sleep behavior disorder is a sleep disorder in which you physically act out vivid, often unpleasant dreams with vocal sounds and sudden, often violent arm and leg movements during REM sleep — sometimes called dream-enacting behavior.

You normally don't move during REM sleep, a normal stage of sleep that occurs many times during the night. About 20 percent of your sleep is spent in REM sleep, the usual time for dreaming, which occurs primarily during the second half of the night.

The onset of REM sleep behavior disorder is often sudden, and episodes may occur occasionally or several times a night. The disorder can get worse with time.

REM sleep behavior disorder often may be associated with other neurological conditions, such as Lewy body dementia (also called dementia with Lewy bodies), Parkinson's disease or multiple system atrophy.

Respiratory syncytial virus (RSV) is a virus that causes infections of the lungs and respiratory tract. It's so common that most children have been infected with the virus by age 2. Respiratory syncytial (sin-SISH-ul) virus can also infect adults.

In adults and older, healthy children, the symptoms of respiratory syncytial virus are mild and typically mimic the common cold. Self-care measures are usually all that's needed to relieve any discomfort.

Infection with respiratory syncytial virus can be severe in some cases, especially in premature babies and infants with underlying health conditions. RSV can also become serious in older adults, adults with heart and lung diseases, or anyone with a very weak immune system (immunocompromised).