Approved indications
Intramuscular Tigan is approved in adults for treatment of postoperative nausea and vomiting and for nausea associated with gastroenteritis; the injectable form is not recommended for pediatric patients because of a higher risk of serious nervous system side effects.

Off-label uses and evidence
Clinicians may occasionally use trimethobenzamide as a later-line option for nausea and vomiting from other causes, such as pregnancy-related nausea, when standard therapies fail; evidence for these off-label uses is limited and it is generally considered less favored than newer antiemetics.

Efficacy expectations
After an intramuscular injection, symptom relief typically begins within about 15–35 minutes and lasts 2–3 hours, with many patients experiencing partial or complete reduction of nausea and vomiting during this period. Overall, its effectiveness is modest and, due to safety concerns and the availability of better-tolerated agents (such as ondansetron or other modern antiemetics), it is now used less often as a first-choice treatment and more when other options are unsuitable or ineffective.

Typical adult dosing
For adults with postoperative or gastroenteritis-related nausea and vomiting, a usual intramuscular dose is 200 mg given three or four times daily, using the lowest effective total daily dose. The injection is formulated as 100 mg/mL, so a typical dose is 2 mL per injection.

Administration instructions
The injection is for intramuscular use only and should not be given intravenously. It should be injected deeply into a large muscle, typically the upper outer quadrant of the gluteal muscle, to reduce pain and local irritation, and care should be taken to avoid leakage of solution along the needle track. It may be given without regard to meals, but patients should avoid alcohol and other sedating drugs unless specifically directed.

Special dosing considerations
In older adults and in patients with reduced kidney function (creatinine clearance about 70 mL/min/1.73 m² or less), the total daily dose should generally be reduced by increasing the interval between injections, with adjustments guided by response and tolerability. Intramuscular Tigan should not be used in pediatric patients.

Missed dose guidance
If a scheduled dose is missed and nausea or vomiting persists, the dose can usually be taken when remembered, but if it is almost time for the next dose, the missed dose should be skipped to avoid double dosing. Patients receiving injections in a clinic or hospital will typically follow that facility’s dosing schedule.

Overdose
Overdose may cause profound drowsiness, severe extrapyramidal reactions, seizures, coma, hypotension, or serious heart rhythm or breathing problems; emergency medical care and contact with a poison control center are warranted, and management is supportive with close monitoring.

Common side effects
Common effects include drowsiness, dizziness, headache, blurred vision, diarrhea or stomach upset, and pain, burning, redness, or swelling at the injection site; these usually appear soon after dosing and are often mild to moderate. Some people may feel slowed thinking or impaired coordination, so caution is advised with driving or operating machinery.

Serious or rare adverse effects
Serious reactions can include extrapyramidal symptoms (involuntary muscle spasms, twisting movements, oculogyric crisis, neck or jaw stiffness, restlessness or Parkinson-like symptoms), severe confusion or disorientation, seizures, coma, marked low blood pressure, jaundice or other signs of liver injury, and severe allergic reactions such as rash, swelling, or trouble breathing; these require urgent medical attention and discontinuation of the drug.

Warnings and precautions
The intramuscular injection should not be used in children or adolescents because of increased risk of extrapyramidal and other serious central nervous system effects. Use caution in older adults, and in people with kidney impairment, with dose adjustment or longer dosing intervals. Avoid use in patients with known liver disease or a history of trimethobenzamide-associated jaundice, and use carefully in conditions such as suspected Reye’s syndrome. During pregnancy, trimethobenzamide is generally reserved for situations where potential benefits outweigh risks and other safer options are inadequate; data in breastfeeding are limited, so monitoring the infant for sedation or feeding problems is advised if it is used. Because it can cause sedation and additive central nervous system depression, use carefully with alcohol, opioids, benzodiazepines, sedating antihistamines, antipsychotics, or other sedatives.

Comparative safety
Compared with many newer antiemetics, trimethobenzamide has a higher risk of extrapyramidal and other central nervous system reactions, so it is typically not a first-line choice when safer alternatives are available.

Reporting side effects and safety updates
Suspected side effects can be reported to the FDA MedWatch program (online or by phone), and patients can check FDA safety communications or package inserts for the most current safety information about Tigan.

Drug and substance interactions
Trimethobenzamide can increase sedation and impairment when combined with alcohol, opioids, benzodiazepines, sedative-hypnotics, barbiturates, sedating antihistamines, antipsychotics, or other central nervous system depressants. Concomitant use with other dopamine-blocking drugs (such as many antipsychotics or metoclopramide) can increase the risk of extrapyramidal symptoms. Anticholinergic drugs used to treat dystonia may be given if extrapyramidal reactions occur, but routine combination is generally avoided unless clinically indicated.

Food, supplements, and diagnostic procedures
No specific food or dietary supplement interactions are well documented, but patients should be cautious with other agents that cause drowsiness or affect the nervous system. Trimethobenzamide is not known to significantly interfere with common laboratory or imaging studies, though severe liver injury, if it occurs, can alter liver test results.

Conditions and co-medications requiring caution
Use with caution or avoid in patients with known liver disease, prior trimethobenzamide-induced jaundice, suspected or confirmed Reye’s syndrome, seizure disorders, Parkinson’s disease or other movement disorders, significant kidney impairment, or in older adults who are more sensitive to sedative and extrapyramidal effects. The intramuscular formulation should not be used in pediatric patients.

Monitoring needs
Clinicians typically monitor for improvement of nausea and vomiting, drowsiness, confusion, and any signs of extrapyramidal symptoms such as muscle spasms, abnormal movements, or restlessness. In patients receiving repeated doses or with risk factors, periodic assessment of kidney function and, if symptoms suggest liver injury (e.g., jaundice, dark urine, right upper abdominal pain), liver tests may be considered.

Q: What is Tigan (trimethobenzamide) injection used for?
A: The intramuscular form of Tigan is used mainly in adults to help prevent or treat nausea and vomiting after surgery or due to gastroenteritis when other treatments are not suitable or sufficient.

Q: How quickly will an intramuscular dose of Tigan start to work?
A: After a deep intramuscular injection, Tigan typically begins to reduce nausea and vomiting within about 15–35 minutes, and its effect usually lasts a few hours.

Q: Can children receive Tigan injections for nausea?
A: No, the intramuscular formulation of trimethobenzamide is not recommended for children or adolescents because it carries a higher risk of serious nervous system side effects in this age group.

Q: Is it safe to drink alcohol while using Tigan?
A: Alcohol should be avoided because it can add to the drowsiness and dizziness caused by Tigan and increase the risk of accidents or other side effects.

Q: What should I watch for as warning signs while getting Tigan injections?
A: Seek medical attention promptly if you notice severe muscle spasms or twisting movements, difficulty speaking or swallowing, high restlessness, severe confusion, yellowing of the skin or eyes, a rash or trouble breathing, or any other sudden, severe change in how you feel.

Storage
Store Tigan intramuscular vials at controlled room temperature, about 68–77°F (20–25°C), and protect them from excessive heat, cold, and light; do not freeze.

Handling and Disposal
Keep vials and used needles/syringes out of the reach of children and pets, and do not reuse needles or syringes; place used sharps in a puncture-resistant sharps container and follow local or pharmacy guidance for disposal of sharps and any unused or expired medicine.