Ineffective Results

• Only about half of cats actually respond to catnip, and young kittens entirely lack the receptors necessary for enjoying the herb. Cats may develop an aversion to catnip if they do not react to its psychoactive properties.
  
  

Sedative Versus Stimulant Effects

• Catnip has a caffeinelike stimulant effect on cats when it is sniffed. However, it actually acts as a sedative when it is eaten.
  
  

Diuretic Side Effects

• In humans, catnip may have mild diuretic effects. Anecdotal evidence has suggested that cats exposed to catnip urinate more frequently.
  
  

In Pregnancy

• The medicinal use of catnip is contraindicated during pregnancy in humans, because it may stimulate contractions of the uterus. Catnip should be used with caution for pregnant cats.
  
  

Precaution

• No reports of cats having serious or life-threatening reactions to catnip exist, but pet owners should ask a veterinarian before giving catnip to any animal with a serious medical condition.