Find answers to your health-related questions in our health encyclopedia.

  • Disease

    Nabothian cyst

    The cervix is lined with glands that normally secrete mucus. These endocervical glands can become filled with secretions that accumulate as a pimple-like elevation called Nabothian cysts. These cysts are not a threat to health and no treatment is necessary.

    A nabothian cyst is a mucus-filled lump on the surface of the cervix. The cervix is located at the lower end of the womb (uterus) at the top of the vagina....

  • Symptoms

    Nail abnormalities

    A paronychia is an infection around the nail. Many organisms can cause a paronychia. This particular case is caused by the yeast-like organism Candida. Note the inflammation (red, swollen area) at the base of the nail and the changes that are apparent in the nail itself.

    Nail abnormalities are problems with the color, shape, texture, or thickness of the fingernails or toenails.

  • Special Topic

    Nail care for newborns

    Newborns have fingernails that are usually soft and flexible but that can cause injuries to the infant because they do not yet have control of arm, hand, and finger movements and may inadvertently claw at their face. Nails should be carefully trimmed with small, blunt-tipped scissors. Use an emery board to keep the nails smooth.

    Newborn fingernails and toenails are most often soft and flexible. However, if they are ragged or too long, they can hurt the baby or others. It is important...

  • Self-Care Instructions

    Nail injuries

  • Poison

    Nail polish poisoning

    This poisoning is from swallowing or breathing in (inhaling) nail polish. This article is for information only. DO NOT use it to treat or manage an actual...

  • Poison

    Naphthalene poisoning

    Naphthalene is a white solid substance with a strong smell. Poisoning from naphthalene destroys or changes red blood cells so they cannot carry oxygen. This...

  • Poison

    Naproxen sodium overdose

    Naproxen sodium is a nonsteroidal anti-inflammatory drug (NSAID) used to relieve mild to moderate aches and pains. Naproxen sodium overdose occurs when...

  • Disease

    Narcissistic personality disorder

    Narcissistic personality disorder is a mental condition in which a person has: An excessive sense of self-importance An extreme preoccupation with...

  • Disease


    Sleep patterns change with age, anxiety levels and many other factors. Normally, younger people have more concentrated periods of deep sleep compared to older people.

    Narcolepsy is a nervous system problem that causes extreme sleepiness and attacks of daytime sleep.

  • Special Topic

    Nasal CPAP

    CPAP is an airway treatment that applies a constant pressure of forced air to keep the airway open.

    CPAP stands for continuous positive airway pressure. CPAP pumps air under pressure into the airway of the lungs, keeping the windpipe open during sleep. The...