Mechanical Poisons


► Mechanical poisons are not poisons as they do not produce toxic effects but cause local irritation at the site of application. For example, glass powder can cause irritation of gastrointestinal mucosa if ingested. These agents are considered as “unwholesome drugs” or other drugs of the section 328 of IPC.

► They are not absorbed into the body but cause mechanical obstruction in gastrointestinal tract.

► They cause irritation, perforation and obstruction due to their edges or sharp points.

Examples are:

Fatal dose and Fatal Period


Signs and Symptoms

  • Pain in Abdomen.
  • Nausea
  • Vomiting
  • Bleeding in tissue
  • Death due to hemorrhagic shock, perforation in stomach and intestine.
  • Irritation
  • GIT mucosa may be inflamed.


  • Bowel/esophagus perforation
  • Mechanical intestinal obstruction
  • GIT hemorrhage
  • Perforation peritonitis


  • Bulky food and then purgatives to pass the irritants in stools.
  • Ice pieces to reduce thirst.
  • Analgesics to relieve pain.

Autopsy Findings

● Erosions may be noted in mouth, pharynx, esophagus, stomach and intestine.

● Fragments of glass, stone, hairs, etc. may be found in GIT adhered to mucosa.

● Mucosa of GIT may be inflamed.

Medicolegal Importance

● Accidental ingestion may occur with jam, jelly or food, etc.

● Show-men may swallow glass particles while showing the show.

● These agents may be used with an evil intention to cause ill health and death.

● Occasionally used as cattle poisons.

● Children having access to these substances may accidentally ingest them or may inhale in respiratory tract causing respiratory obstruction.

Powdered Glass


● There is sharp and severe burning pain in throat and stomach when it is taken in through mouth.

● Nausea and vomiting may follow.

● The sharp ends of glass may cause severe erosion of the oesophagus, stomach and intestine leading to severe bleeding or perforation. Generally, constipation occurs but diarrhoea may also be seen with blood.

Fatal Dose

Uncertain (Even large doses are sometimes not fatal)

Fatal Period

Uncertain (Death may occur in hours to days)


● Give bulky food like bananas, rice or isabgol. After that, purgative may be given.

● Antacids may be given later to soothe gastric or oesophageal mucosa.

● If sharp ends are present, one may have to resort to surgery to remove pieces.

Postmortem Appearance

● Erosion is widely seen in mouth, pharynx, oesophagus, stomach and intestine.

● Fragments of glass are seen adhered to stomach wall.

● The mucosal membranes are congested and inflamed.

Medicolegal Aspect

● It is a general belief that glass is highly poisonous. So, it is given for homicidal purposes by mixing it in food like rice or vegetables.

● Powdered glass is rarely used for suicidal purposes. It may be used for killing cattle.

● Many artists show eating of glass in circuses and public shows.

Diamond Powder

● Diamond powder belief to be toxic but it is not.

● Diamond powder causes irritation in the gastrointestinal tract due to its sharp and prominent edges.

● The treatment includes giving bulky food and then laxatives.

● Antacids may be given to soothe gastric and intestinal mucosa. A criminal may swallow diamonds to steal or escape from police search.

Needles and Pins

● Needles and pins when consumed through oral route cause severe burning pain and irritation in the oesophagus and stomach.

● Due to very sharp edges it may cause perforation or may be impacted in mucosa wall.

● Death may occur due to perforation.

●Treatment includes giving bulky food and then laxatives. But sometimes, surgery may be required to remove needles and pins as they are impacted in the mucosa wall. X-ray examination is quite helpful in locating the exact site of impaction.

● Needles and pins may be accidentally ingested while working. Such incidents are common in children. Suicides and homicides are rare.

Chopped Animal Hairs

► It is a general belief that chopped animal hairs are quite poisonous but it is not true.

► They cause irritation in the stomach and may cause vomiting and diarrhoea.

► Sometimes, they are given to animals to kill them but rarely do they cause any harm. At times, if they are not excreted out through faeces, they may cause intestinal obstruction and digestive disorders. Sometimes, chopped animal hairs are given in the food to punish someone rather than kill him.

Vegetables Hairs

► These are fine, short hairs derived from leaves and stalks of certain plants and called stinging hairs.

► They cause mechanical irritation when they come into contact with skin or mucosa.

► Sometimes, these hairs have short bulbs attached to them which contain irritant fluid consisting of histamine and acetyl choline.

► The fluids also cause irritation when they come in contact with skin.

► Treatment includes washing the area where the juice has come in contact with, with water and later anti-septic and anti-inflammatory lotion may be applied.

► If these vegetable hairs are ingested, bulky food may be given followed by laxatives.

► Cases have been reported where these hair have been applied to fellow-passengers in train to produce irritation with a view to divert attention to rob the person.


  1. Dr. K.S. Narayan Reddy. The essential of forensic medicine and toxicology.34th edition.
  2. VV Pillay.Modern medical toxicology.4th edition.
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