Horse Nettle Poisoning

Medically Reviewed by Dany Paul Baby, MD on November 04, 2022
5 min read

Just because a plant is pretty doesn’t mean it’s safe to be around. The horse nettle plant is one example. The star-shaped flowers might look nice in a garden, but the sharp thorns and the poison they hold make the horse nettle a plant to avoid.

Horse nettle (Solanum carolinense) is also sometimes called Carolina horse nettle. Despite the name, Carolina horse nettle isn’t exclusive to the Carolinas. It’s found in much of the U.S., from east Texas up to Iowa and all along the east coast from Florida up to southern Maine. 

The horse nettle plant is a weedy herb that blooms from May through October. Its taproots, roots that grow vertically, can reach a depth of five feet, but the main stalk of the plant only grows 1-3 feet tall. Horse nettle prefers full sun but can grow in wet and dry conditions. It can grow in most soil types but grows best in disturbed sandy and gravelly soil.

Bumblebees and other insects are the primary pollinators of horse nettle. Wild birds like quail and wild turkey eat the fruit. Humans and most animals should not eat horse nettle, as the entire plant is poisonous. There are generally no uses for horse nettle.

The horse nettle plant has wide-spread branches scattered with thorns. It’s got alternating leaves, which are 2-4 inches long and oval-shaped with wavy edges. The veins of the leaves have small prickles.

When horse nettle blooms, the plant displays clusters of light violet to white star-shaped flowers with yellow stamens sticking out from the center. If the flowers are pollinated, berries will develop. They are glossy and green then turn yellow when ripe.

General tips for horse nettle identification:

  • Sprawling perennial reaching 1-3 feet tall
  • Prickly stems
  • 2-4 inch oval leaves with wavy edges
  • Light violet to white star-shaped flowers
  • Bright yellow, protruding stamens
  • Green berries that turn yellow as they ripen

The genus Solanum is part of the Solanaceae family, commonly known as the nightshade family. Plants in this family include foods we often eat, like potatoes, tomatoes, and eggplant, but also more dangerous plants like the deadly belladonna.

Plants in the Solanaceae family contain a toxin called solanine that can cause illness and even death when eaten. The plants we eat usually have very low levels of solanine. For example, the average person would have to eat about 12 eggplants in one sitting for the solanine to have any effect.

The most common cause of solanine poisoning is ingesting potatoes that have turned green. The green part itself is not the issue, as that’s just chlorophyll, but it indicates the presence of solanine.

The entire horse nettle plant contains solanine, but the amount can vary wildly between plants. The berries, especially while unripe, contain the most toxin, followed by the leaves, stems, and roots.

Symptoms of solanine poisoning usually start 8-10 hours after eating the plant. Symptoms mostly affect the gastrointestinal system, but large amounts of solanine toxin can affect the nervous system. Symptoms of solanine poisoning include:

  • Agitation
  • Changes in vision
  • Confusion
  • Diarrhea and vomiting
  • Fever
  • Hallucinations
  • Headache
  • Lower than normal body temperature
  • Nausea
  • Numbness and tingling
  • Pain in the stomach or abdomen
  • Paralysis
  • Shock
  • Slowed pulse
  • Slowed breathing

If you discover that you or a loved one has ingested horse nettle, you need to call poison control. Before you do, make sure to have this information ready:

  • Age of the person who swallowed the horse nettle
  • Weight of the person who swallowed the horse nettle
  • Current symptoms of the person who swallowed the horse nettle
  • How much of the plant was swallowed
  • When the plant was swallowed

All of these things can impact how severe the poisoning may be. Poison control will be able to take this information and give you further instructions, like advising you to go to the emergency room. You can reach the national toll-free poison hotline at 1-800-222-1222.

Poison control may recommend that you go to the hospital. There is no antidote for solanine. The hospital will likely monitor your vital signs like your blood pressure, heart rate, and body temperature, and may run some tests. Treatment for solanine poisoning involves managing the symptoms until the poison leaves your body. This may include:

  • Breathing assistance, such as intubation
  • Fluids through an IV
  • Medications to manage symptoms

Symptoms usually last from one to three days, but it depends on how much you swallowed and if you received medical care. Proper medical care can usually lead to a full recovery within five to seven days.

The flowers of the horse nettle plant are striking, but they don’t make very good plants for a garden. Their deep roots make them difficult to control and the plants can grow aggressively. The prickly stems and poisonous nature of the plants make them particularly unsafe for families with small children or outdoor pets.

Luckily, there are a few other species of plants that produce pretty, star-shaped flowers that are safe for your garden.

Bellflowers. Bellflowers come from the Campanula genus and are incredibly diverse, with 500 different species of flowers. Bellflowers come in shades of blue, pink, purple, and white, and while many of them have bell-shaped blossoms that give bellflowers their name, many others have a star-shaped look similar to the flowers of horse nettles. These include:

  • Milky bellflower (Campanula lactiflora): Milky bellflower plants grow to almost five feet tall and have light purple star-shaped flowers.
  • Serbian bellflower (Campanula poscharskyana): The Serbian bellflower grows close to the ground and produces pale purplish blue star-shaped flowers.
  • Spanish bellflower (Campanula primulifolia): The Spanish bellflower offers bunches of purple star-shaped flowers with dark purple stamens.

Pentas. Pentas flowers thrive in tropical climates, like Florida. These plants grow wide and a few feet tall, like horse nettles. Pentas flowers are star-shaped and come in shades of pink, red, and white.

Star tulips. Contrary to their name, the star tulip (Calochortus monophyllus) is actually a type of lily. The yellow star tulip has clusters of bright yellow star-shaped flowers with bright yellow stamens.