One main difference between valerian and passion flower is that the root of the valerian plant is used for herbal supplements, but only the above-ground parts of the passion flower plant are used for medicinal purposes. Some passion flower species bear edible fruit known as passion fruit, but the valerian plant produces only flowers. Another difference between valerian and passion flower is that valerian, when taken alone, might cause increased tiredness and sometimes is considered to be a stronger medicinal herb than passion flower.

Valeriana officinalis is the Latin name for the perennial valerian plant, which displays white and pink flowers that give off a sweet aroma. During the 16th century, the valerian flowers were used in perfumes. The root of the valerian plant is commonly used in teas, tinctures, oils, liquid extracts, infusions and capsule form and is said to promote emotional well-being by relaxation of the central nervous system.

The Latin name for the passion flower plant is Passiflora, and it has more than 500 species. Most plants grow as a vine or shrub, with some species bearing an egg-shaped tropical fruit commonly known as passion fruit. The stems, leaves and flowers of the passion flower plant are used in herbal supplements, often blending with other, more potent herbs to achieve an appropriate balance. The passion flower supplement has a sedative effect.

Valerian and passion flower often are combined to make an herbal supplement blend to aid in the treatment of disorders such as anxiety or panic attacks, insomnia and mild mood swings. This blended compound is a preferred treatment for these disorders, because it usually is non-addictive. Taken in the recommended dosages, it generally is considered to be safe and nontoxic. Certain depressants, such as benzodiazepines, alcohol and barbiturates, should not be used while taking valerian or passion flower, because these herbal supplement compounds produce central nervous system depression.

Not many adverse side effects have been reported by users of valerian and passion flower, but as with any medicine or supplement, a doctor should be consulted prior to use. A difference between valerian and passion flower is that valerian taken in large doses might cause an upset stomach. In very rare cases, an allergic reaction such as a skin rash or hives has been noted. The herbs have tranquilizing properties, so driving and operating heavy equipment should be avoided.

The difference between valerian and passion flower actually is small in regard to their medicinal qualities. The passion flower usually is considered less potent than valerian. When blended, they complement each other and balance their effectiveness in the treatment of many central nervous disorders.