Mention colds and most people think of clogged heads and runny noses. But cold sufferers also often have raw sore throats and laryngitis, one of the more baffling complications of colds.

Doctors don't know exactly what causes the condition or why some people are more prone to it than others. So far, there is no drug to cure laryngitis, although there are simple remedies to help sufferers.

Exposure to chemicals, such as formaldehyde; smoking cigarettes or breathing second-hand smoke sometimes can produce laryngitis. So can straining the voice by singing, shouting or simply talking too much.

Although the result is the same -- a hoarse, croaking whisper -- laryngitis associated with colds is produced by the same constellation of viruses that are responsible for stuffy noses. The difference is that in some people the viruses seem to favor the larynx. Bacterial infections can also result in a bad case of laryngitis.

Some people are clearly more prone to laryngitis than others. One theory is that a large number of cases are caused by parainfluenza, a virus known to cause croup in babies and young children.

Some researchers theorize that children who have croup grow up to be adults who suffer from laryngitis. "But there's no scientific evidence yet for that," said Texas otolaryngologist Stephen Mitchell.

Whatever its cause, laryngitis produces an inflammation and swelling of the larynx. Vocal cords within the larynx are like tiny, delicate musical instruments. When they're swollen, they can't vibrate properly. "The result is that you lose your voice," said David Fairbanks, a Fairfax County physician and spokesman for the American Academy of Otolaryngology.

As with colds, there is no specific drug treatment for laryngitis caused by a virus. And some drugs, such as antihistamines, which dry the throat, will often make it worse. Hot liquids such as tea or soup, humidifiers and breathing the steam produced in a shower will probably help. Throat lozenges and hot tea stimulate secretions and help relax the vocal cords. Gargling with warm salt water may also help by washing away virus or bacteria from the infected larynx.

The best remedy is to rest the voice. Talking, and especially whispering, only makes it worse. That's because whispering strains the vocal cords more than speaking in a normal voice. It also uses more air, which helps further dry the larynx.

"If you must talk, use whatever voice you can normally carry a pitch in," advised Mitchell. Try to speak in a breathy voice that comes not from your throat but from your diaphragm.