Entecavir Tablet Side Effects in Pakistan

Complete guide to Entecavir (Ecavir, Baraclude) side effects. The medicine is generally well tolerated, but it is essential to know about stopping-related HBV flare and lactic acidosis.

Compiled by the PakVita Editorial Team · AI-assisted drafting with editorial review · Sourced from DRAP, WHO, BNF · Last updated: 2026-06-17

Side Effects

Quick Answer

Entecavir is generally very well tolerated. Common side effects are minimal — headache, fatigue, nausea. Serious risks: lactic acidosis (rare — abdominal pain, vomiting, muscle weakness) and severe HBV flare if treatment is suddenly discontinued (potentially fatal). NEVER discontinue without a specialist.

Side Effects at a Glance

Common

Headache
Fatigue
Dizziness
Nausea
Elevated liver enzymes (transient — ALT/AST rise)
Upper respiratory infection-like symptoms (runny nose, sore throat)

Serious — See a Doctor

Lactic acidosis
Severe HBV flare on stopping treatment (jaundice, dark urine, severe fatigue — EMERGENCY liver failure risk)
Nephrotoxicity (rare — renal function decline)
Exacerbation of hepatitis (immune reconstitution in HIV co-infection)

When to See a Doctor Immediately

Severe abdominal pain + persistent vomiting
Severe jaundice / dark urine
Muscle weakness / myopathy (lactic acidosis)
Breathlessness without clear cause (lactic acidosis)
Any symptoms after stopping treatment (HBV rebound — EMERGENCY)
Significant fatigue + nausea that persists for days

Entecavir Tablet Side Effects

Entecavir (Ecavir, Baraclude) is generally a very well tolerated medicine. However, there are some serious risks — it is especially important to know about stopping treatment and lactic acidosis.

Common Side Effects (Generally Mild)

Headache
Fatigue
Dizziness
Nausea
Transient elevation of LFTs (ALT/AST — usually benign)
URTI-like symptoms (runny nose, sore throat)

These side effects are generally mild and self-limiting. If they persist or worsen, inform your doctor.

Serious Side Effects

Lactic Acidosis (Rare but Serious)

Class effect of nucleoside analogues — especially with hepatic steatosis or decompensation:

Symptoms: Severe abdominal pain, persistent vomiting, muscle weakness, breathlessness, unexplained metabolic acidosis
Action: STOP Entecavir IMMEDIATELY and go to 1122 / nearest emergency — life-threatening

Severe HBV Flare on Stopping (Most Important Warning)

A severe hepatitis B flare can occur after stopping Entecavir:

Symptoms: Jaundice, dark urine, severe fatigue, right upper abdominal pain
Risk: Liver failure and death — EMERGENCY
Prevention: NEVER discontinue without a specialist

Nephrotoxicity (Rare)

Renal function decline — less common than with adefovir
Regular creatinine/eGFR monitoring is necessary

HIV Co-infection Exacerbation

Immune reconstitution hepatitis flare can occur in HIV/HBV patients

Side Effects Summary Table

Type	Side Effect	Action
Common	Headache, fatigue, nausea	Monitor — inform doctor if it persists
Serious	Lactic acidosis	STOP + EMERGENCY IMMEDIATELY
Serious	HBV flare on stopping	EMERGENCY — see specialist
Rare	Nephrotoxicity	Renal monitoring

Reporting Side Effects

If you notice any unexpected side effect, report it on the DRAP pharmacovigilance portal: https://www.dra.gov.pk/pharmacovigilance

When to See Doctor Immediately

Severe abdominal pain + vomiting → lactic acidosis → STOP + 1122
Jaundice / dark urine / severe fatigue → HBV flare or hepatotoxicity → EMERGENCY
Muscle weakness + breathlessness → lactic acidosis
Symptoms after stopping treatment → HBV rebound → EMERGENCY

The information in this guide is for educational purposes only. If you notice any side effect, contact your doctor or pharmacist.

Frequently Asked Questions

What are the side effects of Entecavir?

Entecavir is generally well tolerated. Common effects: headache, fatigue, nausea. Serious: lactic acidosis (rare — severe abdominal pain, muscle weakness) and HBV flare after stopping treatment (dangerous). Inform the doctor immediately if any severe symptom occurs.

What happens after stopping Entecavir?

Suddenly stopping Entecavir can cause a severe HBV flare — liver inflammation increases, jaundice develops, and liver failure can occur — potentially fatal. NEVER discontinue without a specialist.

What is lactic acidosis and why does it occur with Entecavir?

Lactic acidosis is a rare but serious side effect — a class effect of nucleoside analogues (Entecavir's class). Mitochondrial dysfunction causes lactic acid buildup. Symptoms: severe abdominal pain, vomiting, muscle weakness, breathlessness. Seek emergency care IMMEDIATELY.

Does Entecavir affect the kidneys?

Nephrotoxicity from Entecavir is rare (less than adefovir). However, renal function monitoring is necessary — dose reduction is required in renal impairment.

Is long-term use of Entecavir safe?

Yes — Entecavir is generally safe and well tolerated with long-term use. Regular monitoring (LFTs, HBV DNA, renal function) ensures safety.

Sources

BNF: Entecavir — BMJ Group & Pharmaceutical Press
DRAP Registered Products Database — Drug Regulatory Authority of Pakistan
WHO Model List of Essential Medicines, 23rd ed. (2023) — World Health Organization
British National Formulary (BNF) — BMJ Group & Pharmaceutical Press

Medical disclaimer

This page is for educational use only and does not replace professional medical advice. Always confirm diagnosis, dose, and interactions with a qualified doctor or pharmacist before starting or changing any medicine.