Isoniazid 300mg Tablet: Complete Medicine Guide
Clinical Reference Standards: CDSCO (Central Drugs Standard Control Organisation), Indian Pharmacopoeia (IP) & WHO | Last Updated: September 2026
When to Call Your Doctor IMMEDIATELY
- Yellowing of the eyes or skin
- Dark urine or pale stools
- Severe tiredness or weakness
- Persistent nausea and vomiting
- Upper abdominal pain
- Numbness or tingling in hands and feet that worsens
- Seizures or confusion
- Difficulty breathing or swelling of the face, lips, or throat
If experiencing severe symptoms, call emergency services immediately.
What is isonex 300mg tablet used for?
Isoniazid 300 mg tablet is an antibiotic used to treat and prevent tuberculosis. It works by killing the tuberculosis bacteria. It is usually taken once daily as part of a combination regimen and should never be stopped early without medical advice.
- Generic Name: Isoniazid (300mg)
- Manufacturer: Pfizer Ltd
- Form: Allopathy
- Pregnancy Category: Consult doctor
- Prescription Required: Yes
🇮🇳 isonex 300mg tablet के बारे में (Hindi Summary)
उपयोग: यह दवा इनोनियाजिड 300 मिलीग्राम टैबलेट के रूप में उपलब्ध है और यह तपेदिक (टीबी) के इलाज और रोकथाम के लिए इस्तेमाल की जाती है। यह टीबी के बैक्टीरिया को मारती है और आमतौर पर अन्य टीबी की दवाओं के साथ दी जाती है। इसे रोज एक बार लिया जाता है और डॉक्टर की सलाह के बिना बंद नहीं करना चाहिए। यह दवा खासकर उन लोगों के लिए है जिन्हें सक्रिय टीबी या छिपी हुई टीबी है। जिन लोगों को लीवर की बीमारी है या इस दवा से एलर्जी है, उन्हें यह दवा नहीं लेनी चाहिए।
साइड इफेक्ट्स: इस दवा के आम दुष्प्रभावों में हाथ-पैरों में झनझनाहट या सुन्नपन, जी मिचलाना, उल्टी, भूख न लगना और थकान शामिल हैं। गंभीर दुष्प्रभावों में लीवर को नुकसान, पीलिया, गहरे रंग का पेशाब, और दौरे पड़ना शामिल हो सकते हैं। अगर आपको ऐसे लक्षण दिखें तो तुरंत डॉक्टर से मिलें। डॉक्टर अक्सर विटामिन बी6 भी देते हैं ताकि झनझनाहट से बचाव हो सके।
सुरक्षा सलाह: इस दवा को डॉक्टर के बताए अनुसार ही लें और समय पर लें। शराब बिल्कुल न पिएं क्योंकि इससे लीवर को गंभीर नुकसान हो सकता है। अगर आपको लीवर या किडनी की बीमारी, मधुमेह, या दौरे की समस्या है तो डॉक्टर को पहले बताएं। एल्युमिनियम वाले एंटासिड के साथ यह दवा न लें। नियमित जांच कराते रहें और डॉक्टर की सलाह के बिना दवा बंद न करें।
💊 isonex 300mg tablet Uses & Benefits
[{"condition":"Active pulmonary tuberculosis","description":"This medicine is a first-line component of combination therapy for drug-susceptible pulmonary tuberculosis.","evidence":"Well-established"},{"condition":"Extrapulmonary tuberculosis","description":"This medicine is used in combination regimens for tuberculosis affecting lymph nodes, bones, joints, meninges, and other organs.","evidence":"Well-established"},{"condition":"Latent tuberculosis infection","description":"This medicine is used to prevent progression to active tuberculosis in people with latent infection or recent close contact with an infectious case.","evidence":"Well-established"},{"condition":"Tuberculosis in people living with HIV","description":"This medicine forms part of antitubercular therapy in HIV-positive individuals, with careful attention to drug interactions.","evidence":"Well-established"}]
Off-label uses: [{"condition":"Atypical mycobacterial infections","description":"Sometimes used in combination regimens for certain non-tuberculous mycobacterial infections under specialist guidance.","evidence":"Limited"}]
Primary treatment for: Tuberculosis
Also treats: Latent tuberculosis infection, Extrapulmonary tuberculosis, Tuberculosis in HIV-positive patients
📋 Drug Information
| Generic Name(s) | Isoniazid (300mg) |
| Brand Name | isonex 300mg tablet |
| Manufacturer | Pfizer Ltd |
| Packaging / Form | Varies by brand (Allopathy) |
| Therapeutic Class | ANTI INFECTIVES |
| Action Class | Mycolic acid inhibitors- INH |
| Route of Administration | Oral |
| Storage | Store this medicine at room temperature between 15°C and 30°C, away from direct sunlight and moisture. Keep it in the original container with the lid tightly closed. |
| Shelf Life | The shelf life of this medicine is typically 24 to 36 months from the date of manufacture. Check the expiry date on the pack before use. |
| WHO Guideline | The World Health Organization recommends isoniazid as a first-line medicine for the treatment of drug-susceptible tuberculosis and for preventive therapy in eligible individuals. It is always used in combination with other antitubercular medicines for active disease. |
| ICMR Guideline | The Indian Council of Medical Research and the Revised National Tuberculosis Control Programme recommend isoniazid as part of the standard combination regimen for tuberculosis in India, with pyridoxine supplementation when needed. |
👨⚕️ Doctor's Practical Tips
Evidence-based practical advice from experienced clinicians
🔍 Is This Medicine Right for Your Symptom?
Educational reference. Always consult a doctor for diagnosis.
🔬 How This Medicine Works (Pharmacology)
Pharmacokinetics
How It Works
This medicine works by entering the tuberculosis bacteria and being activated by a bacterial enzyme called KatG. Once activated, it interferes with the synthesis of mycolic acid, which is an essential component of the bacterial cell wall. Without a proper cell wall, the bacteria cannot survive and multiply. This medicine is bactericidal against actively growing tuberculosis bacteria, meaning it kills them rather than just stopping their growth.
Mechanism Steps
💡 How to Take isonex 300mg tablet
Strength: This medicine is available as a 300 mg immediate-release tablet for oral use.
Dosage Information
| Adult Dosage | The usual adult dose of this medicine for active tuberculosis is 5 mg per kg of body weight once daily, often with a maximum of 300 mg per day, used in combination with other antitubercular medicines. For latent tuberculosis infection, the dose may be 300 mg once daily for a specified duration. Dose must be individualized by a qualified clinician based on indication, age, weight, renal and hepatic function, and other medicines being taken. |
| Pediatric Dosage | Pediatric dosing of this medicine is based on body weight and must be determined by a pediatrician. It is usually given as part of a combination regimen for tuberculosis. Do not use this medicine in children without a doctor's prescription. |
| Elderly Dosage | Elderly patients may be more sensitive to the side effects of this medicine, especially liver injury and peripheral neuropathy. Liver function should be monitored closely, and vitamin B6 is often prescribed. Dose must be individualized by a qualified clinician. |
| Renal Impairment | In people with severe kidney disease, the dose of this medicine may need to be reduced or the dosing interval lengthened. This must be determined by a qualified clinician based on kidney function tests. |
| Hepatic Impairment | This medicine should be used with caution in people with liver disease. Liver function tests should be checked before and during treatment. Dose reduction or discontinuation may be needed if liver injury occurs, as decided by a qualified clinician. |
| Maximum Daily Dose | The maximum daily dose of this medicine is generally 300 mg for adults, but this may vary depending on the indication and the patient's condition. Always follow your doctor's prescription. |
Dosage Timeline
🍽️ Food Timing Guide
⏰ What to Do If You Miss a Dose
⚠️ Side Effects of isonex 300mg tablet
✅ Common Side Effects
🚨 Serious Side Effects
⚠️ Rare Side Effects
Consult your doctor if you experience any unusual symptoms.
🔬 Drug Interactions
| Drug | Severity | Effect |
|---|---|---|
| Rifampicin | Major | |
| Alcohol | Major | |
| Carbamazepine | Major | |
| Phenytoin | Major | |
| Aluminium-containing antacids | Moderate | |
| Warfarin | Moderate | |
| Ketoconazole | Moderate | |
| Paracetamol | Minor | |
| Corticosteroids | Minor | |
| Tyramine-rich foods | Minor |
🚨 Major Interactions
- Rifampicin
- Alcohol
- Carbamazepine
- Phenytoin
⚡ Moderate Interactions
- Antacids containing aluminium
- Ketoconazole
- Warfarin
🍷 Alcohol Interaction
Alcohol should be completely avoided while taking this medicine. Drinking alcohol increases the risk of serious liver damage and can make side effects worse. If you drink alcohol regularly, tell your doctor before starting this medicine.
🔎 Check Your Other Medicines
Educational tool. Always confirm with your doctor or pharmacist.
🛡️ Safety & Warnings
🚫 Contraindications
["Known allergy to isoniazid or any component of this medicine","Active liver disease or severe liver injury","Previous severe liver reaction to isoniazid","Acute porphyria"]
⚠️ Warnings & Precautions
["This medicine can cause serious liver injury. Avoid alcohol and report symptoms of liver problems immediately.","Peripheral neuropathy is common; vitamin B6 (pyridoxine) is often prescribed to prevent it.","This medicine can interact with many other medicines, so always inform your doctor about all medicines you take.","Do not stop this medicine without your doctor's advice, even if you feel better, to prevent resistance.","People with diabetes may experience changes in blood sugar control; monitor levels closely.","This medicine may cause dizziness or seizures in rare cases; avoid driving if you feel unwell.","Use with caution in people with kidney disease; dose adjustment may be needed."]
🤱 Lactation Safety
This medicine passes into breast milk in small amounts. It is generally considered compatible with breastfeeding when used as prescribed, but the baby should be monitored for jaundice or unusual sleepiness. A qualified clinician should be consulted before breastfeeding while on this medicine.
💊 Overdose Management
Overdose of this medicine can cause severe seizures, metabolic acidosis, and coma. If you suspect an overdose, seek emergency medical care immediately. Treatment may include activated charcoal, benzodiazepines for seizures, and pyridoxine (vitamin B6) given intravenously by a healthcare professional.
⏰ Missed Dose
If you miss a dose of this medicine, take it as soon as you remember. If it is almost time for your next dose, skip the missed dose and continue with your regular schedule. Do not take two doses at the same time to make up for a missed dose.
Additional Safety Advice
Take this medicine exactly as prescribed by your doctor, at the same time each day, and do not skip doses. Avoid alcohol completely while taking this medicine because alcohol increases the risk of liver damage. Tell your doctor if you have any liver disease, kidney disease, diabetes, HIV infection, or a history of seizures before starting this medicine. Your doctor may prescribe vitamin B6 (pyridoxine) along with this medicine to help prevent numbness and tingling in the hands and feet. Do not take this medicine with antacids that contain aluminium, because they can reduce how well this medicine is absorbed. Keep all follow-up appointments and blood tests, especially liver function tests, because this medicine can affect the liver. If you become pregnant or plan to become pregnant, inform your doctor so that your treatment can be adjusted safely. Never share this medicine with anyone else, even if they have similar symptoms.
👴 Special Considerations for Elderly
💡 For Patients Above 65
Elderly patients are at higher risk of liver injury and peripheral neuropathy from this medicine. Liver function should be monitored closely, and vitamin B6 is often prescribed. Dose adjustment may be needed in those with kidney or liver disease. Regular follow-up is important.
🤰 Pregnancy Planning (TTC)
If you are planning to become pregnant, discuss your tuberculosis treatment with your doctor before conception. This medicine is generally considered safe during pregnancy when prescribed for tuberculosis, but liver function should be monitored and vitamin B6 is usually added. Untreated tuberculosis poses a greater risk to both mother and baby.
🏥 Post-Surgery Considerations
If you are scheduled for surgery, inform your surgeon and anaesthesiologist that you are taking this medicine. It can interact with some anaesthetic agents and may affect liver function. Your doctor will advise whether to continue or temporarily stop the medicine around the time of surgery.
🦷 Dental Procedures
Inform your dentist that you are taking this medicine before any dental procedure. It can interact with some medicines used in dentistry, and your dentist may need to adjust your treatment. Maintain good oral hygiene to prevent infections.
💚 Lifestyle Tips for Better Results
🏋️ Exercise Considerations
Mild to moderate exercise is generally safe while taking this medicine. However, if you experience fatigue, dizziness, or numbness in your feet, avoid activities that require balance or coordination until you feel better. Consult your doctor before starting any strenuous exercise programme.
🥗 Diet Recommendations
💼 Impact on Daily Work & Life
This medicine may cause fatigue, dizziness, or numbness in some people, which can affect your ability to drive or operate machinery. If you experience these effects, avoid driving or operating heavy machinery until you feel better. Most people can continue their normal work routine while taking this medicine, but it is important to take it at the same time each day and attend regular follow-up appointments.
🛑 When to Stop This Medicine
Do not stop this medicine without your doctor's advice. Stopping early can lead to treatment failure and drug-resistant tuberculosis. If you experience serious side effects such as liver injury or severe neuropathy, contact your doctor immediately. Your doctor will decide whether to adjust the dose, add another medicine, or stop treatment based on your condition.
📅 Long-Term Use Effects
Long-term use of this medicine is generally safe when monitored appropriately. The main concern is liver injury, which can occur at any time but is more common in people who drink alcohol or have pre-existing liver disease. Peripheral neuropathy can develop with prolonged use, especially if vitamin B6 is not supplemented. Regular monitoring of liver function and neurological symptoms is recommended. Most people complete treatment without long-term complications.
🌿 Non-Medicine Approaches
These can complement medicine but do not replace prescribed treatment.
Alternative antitubercular regimens may be used if this medicine is not tolerated or is contraindicated.
Evidence: Well-establishedAdequate nutrition helps support recovery from tuberculosis and improves treatment outcomes.
Evidence: Well-established💉 Vaccination Considerations
💉 If You're Getting Vaccinated
The BCG vaccine is used to prevent severe forms of tuberculosis in children. This medicine does not interact with vaccines, but live vaccines should be avoided in people with severe immunodeficiency. Consult your doctor for personalised advice.
📦 Storage Guide
✅ DO
Store at room temperature between 15°C and 30°C
❌ DON'T
Do not refrigerate unless specified
✅ DO
Keep in the original container with the lid tightly closed
❌ DON'T
Do not transfer to unmarked containers
✅ DO
Keep away from direct sunlight and moisture
❌ DON'T
Do not store in the bathroom cabinet
✈️ Traveling with This Medicine
When travelling, carry this medicine in its original packaging with a copy of your prescription. Keep it in your hand luggage to avoid loss or temperature extremes. If crossing time zones, continue taking your dose at the same interval as prescribed, but consult your doctor for specific advice. Store it away from direct sunlight and moisture. Check customs regulations for carrying prescription medicines in your destination country.
💰 Cost Analysis & Savings
👥 Real Patient Stories
Educational, anonymized scenarios. Individual results may vary.
💬 Questions Patients Often Ask
A: This medicine starts killing tuberculosis bacteria within hours, but you may not feel better for several weeks. It is important to complete the full course as prescribed.
A: No, you must complete the full course prescribed by your doctor. Stopping early can allow tuberculosis to return and become resistant to treatment.
A: Take the missed dose as soon as you remember. If it is almost time for your next dose, skip the missed dose and continue with your regular schedule. Do not double dose.
A: Yes, this medicine can cause liver injury in some people. Your doctor will monitor your liver function with blood tests. Report symptoms like yellowing of eyes or skin, dark urine, or severe tiredness immediately.
A: No, alcohol should be completely avoided while taking this medicine because it increases the risk of serious liver damage.
🤔 Common Patient Concerns
🔄 Substitutes for isonex 300mg tablet
View AllAlternative brands with exact same active ingredient:
-
isoniazid 300mg tabletCadila Pharmaceuticals Ltd ₹1.75 91.9% CHEAPER
-
lup inh 300mg tabletLupin Ltd ₹10.88 49.4% CHEAPER
-
isonij 300mg tabletSunij Pharma Pvt Ltd ₹11.22 47.8% CHEAPER
-
solonex tabletMacleods Pharmaceuticals Pvt Ltd ₹13.75 36% CHEAPER
Medical Note: Always consult your doctor before switching medications.
🛑 Myths vs. Facts
- Myth: Isoniazid 300 mg tablet can be stopped once symptoms improve.
Fact: Treatment must be completed as prescribed to prevent tuberculosis from returning and becoming resistant. - Myth: Isoniazid 300 mg tablet is safe to take with alcohol.
Fact: Alcohol increases the risk of serious liver damage and should be avoided completely. - Myth: Isoniazid 300 mg tablet alone is enough to treat tuberculosis.
Fact: It must be used in combination with other antitubercular medicines to prevent resistance. - Myth: Isoniazid 300 mg tablet causes liver damage in everyone.
Fact: Most people tolerate it well, but liver function should be monitored, and symptoms of liver injury should be reported immediately.
🔄 Alternative Options
Generic Alternatives
- Isoniazid 300 mg tablet (generic)
Brand Alternatives
- Isoniazid 300 mg tablet