Because cold, allergies and sinusitis can have similar symptoms, it is often difficult for people to distinguish which of these ailments they really have. But there are telltale signs:

• Colds. Although colds can occur at any time, they are more common during the winter months and generally last three to five days. Colds are often associated with more symptoms than just nasal congestion and a runny nose, such as muscle ache, sore throat and fatigue. If cold symptoms last for more than 10 days, it is time to start thinking you may have an allergy or sinusitis instead.
  
  
• Allergies. Although allergies can be perennial, meaning they occur year round, most allergy flare-ups tend to be seasonal. For some people, symptoms are worse in the spring when flowers and trees are in bloom, whereas for others, symptoms worsen in the fall when ragweed is in the air. The hallmark of allergies is itchy eyes and nose with frequent sneezing episodes. Nasal drainage from allergies is typically clear and watery.
  
  
• Sinusitis. Sinusitis is usually associated with facial pressure either above or below the eyes. It is caused by bacterial overgrowth within the sinus cavities, which are air containing spaces in the bones of the face and the skull that surround the eyes.. A sinus infection can be triggered by a cold or allergy flare-up that lasts for more than 10 days and causes the sinus drainage passages to become blocked. The nasal drainage from sinusitis is typically thick and yellow or green in appearance. Mucus often runs down the back of the throat, causing postnasal drip and sore throat. Acute sinusitis is defined as an episode of sinusitis lasting less than four weeks. When infections become prolonged and symptoms last for more than 12 weeks, the term chronic sinusitis is used.