Uses

• Trimethobenzamide is used to treat nausea and vomiting that may occur after surgery or with a certain stomach/intestinal problem (gastroenteritis). Treating vomiting quickly can prevent a serious loss of body water (dehydration).
• This medication is not recommended for use in children due to risk of serious side effects.

How to use Tigan

• Take this medication by mouth as directed by your doctor, usually 3 to 4 times a day.
• The dosage is based on your medical condition, age, and response to treatment. Do not increase your dose or use this drug more often or for longer than prescribed. Your condition will not improve any faster, and your risk of side effects will increase.
• Tell your doctor if your condition lasts or gets worse.

Dose

• The recommended adult dosage is 300 mg orally three or four times daily. Select the lowest effective daily dosage and adjust as needed based upon therapeutic response and tolerability.

Dosage Adjustment for Geriatric Patients and/or Patients with Renal Impairment

• In geriatric patients and/or in patients with renal impairment (creatinine clearance 70 mL/min/1.73m2 or less), reduce the daily dosage of Tigan by increasing the dosing interval and adjust as needed based upon therapeutic response and tolerability.

Side Effects

Diarrhea, headache, dizziness, drowsiness, or blurred vision may occur. If any of these effects last or get worse, tell your doctor or pharmacist promptly.

Remember that your doctor has prescribed this medication because he or she has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.

Tell your doctor right away if you have any serious side effects, including:

• mental/mood changes (such as depression, confusion, restlessness), yellowing eyes/skin, dark urine, muscle spasms, unusual uncontrolled movements (especially of the face, mouth, tongue, arms, or legs), severe arching of the back, shaking (tremor).

Get medical help right away if you have any very serious side effects, including:

• seizures.

A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing.

This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.

Precautions

• Before taking trimethobenzamide, tell your doctor or pharmacist if you are allergic to it; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.
• Before using this medication, tell your doctor or pharmacist your medical history, especially of: liver disease, kidney problems, stomach/intestinal problems (such as appendicitis), swelling/disease of the brain (encephalitis/encephalopathy), a serious loss of body water (dehydration), mineral (electrolyte) imbalance.
• This drug may make you dizzy or drowsy or blur your vision. Alcohol or marijuana (cannabis) can make you more dizzy or drowsy. Do not drive, use machinery, or do anything that needs alertness or clear vision until you can do it safely. Avoid alcoholic beverages. 
• Older adults may be more sensitive to the side effects of this drug, especially unusual uncontrolled movements and shaking.
• During pregnancy, this medication should be used only when clearly needed. Discuss the risks and benefits with your doctor.

Interactions

Drug interactions may change how your medications work or increase your risk for serious side effects. Keep a list of all the products you use (including prescription/nonprescription drugs and herbal products) and share it with your doctor and pharmacist. Do not start, stop, or change the dosage of any medicines without your doctor's approval.

Tell your doctor or pharmacist if you are taking other products that cause drowsiness such as opioid pain or cough relievers (such as codeine, hydrocodone), alcohol, drugs for sleep or anxiety (such as alprazolam, lorazepam, zolpidem), muscle relaxants (such as carisoprodol, cyclobenzaprine), or antihistamines (such as cetirizine, diphenhydramine).

Check the labels on all your medicines (such as allergy or cough-and-cold products) because they may contain ingredients that cause drowsiness. Ask your pharmacist about using those products safely.

Effects On The Ability To Drive Or Operate Machinery

• Tigan can cause drowsiness and may impair the mental and/or physical abilities required for the performance of hazardous tasks such as driving a motor vehicle or operating machinery. Concomitant use of other drugs that cause CNS depression or EPS symptoms (e.g., alcohol, sedatives, hypnotics, opiates, anxiolytics, antipsychotics, and anticholinergics) may increase this effect.
• Patients should not to operate motor vehicles or other dangerous machinery until they are reasonably certain that Tigan does not affect them adversely.

References:

https://www.webmd.com/drugs/2/drug-8399/tigan-oral/details

https://www.rxlist.com/tigan-drug.htm#warnings

https://en.wikipedia.org/wiki/Trimethobenzamide

https://www.pfizermedicalinformation.com/en-us/tigan?section=drug-interactions

https://reference.medscape.com/drug/tigan-trimethobenzamide-342060

https://www.empr.com/drug/tigan/

https://www.pfizer.com/products/product-detail/tigan