Tomatoes are found as a fruit in many places and used as an enhancement in many dishes. Tomatoes are a member of nightshade family. Majority of members of nightshade family are toxic in nature due to presence of alkaloids. The stem and leaves of tomatoes contain the same toxic element . That is why the leaves of tomatoes are not available in commercial market.
Leaves, stems, and green unripe fruit of the tomato plant contain small amounts of the toxic alkaloid tomatine. They also contain solanine, a toxic alkaloid found in potato leaves and other plants in the nightshade family. Use of tomato leaves in herbal tea has been responsible for at least one death. However, levels of tomatine in foliage and green fruit are generally too small to be dangerous unless large amounts are consumed, for example, as greens. Small amounts of tomato foliage are sometimes used for flavoring without ill effect, and the green fruit is sometimes used for cooking, particularly as fried green tomatoes. Compared to potatoes the amount of solanine in green or ripe tomatoes is low; however, even in the case of potatoes while solanine poisoning resulting from dosages several times normal human consumption has been demonstrated, actual cases of poisoning resulting from excessive consumption of potatoes that have high concentration of solanine are rare.
Tomato plants can be toxic to dogs if they eat large amounts of the fruit, or chew plant material.
Tomatoes were linked to seven salmonella outbreaks between 1990 and 2005, and may have been the cause of a salmonellosis outbreak causing 172 illnesses in 18 U.S. states in 2006, The 2008 United States salmonellosis outbreak also caused the removal of tomatoes from stores and restaurants across the United States and parts of Canada, although other foods, including jalapeño and serrano peppers, may have been involved.