Here are the known side effects of posaconazole (Candipoz-GR 300) and how they may explain the stomach pain, burning at the sides, poor sleep and low appetite.

🩺 Symptoms

• Stomach pain, burning at the sides, and reduced appetite are listed gastrointestinal (GI) effects of posaconazole; product information and internal reports note heartburn, nausea, vomiting, diarrhoea and decreased appetite.
• Sleeplessness can occur as a less common systemic reaction or secondary to ongoing pain/discomfort.

⚕️ What this likely is

• Medication-related GI side effects: posaconazole commonly causes GI upset that fits the described symptoms.
• Drug-induced gastritis or acid reflux producing burning/side pain and loss of appetite.
• Less likely: another medication or unrelated GI condition — consider interactions or prior stomach disease.

💊 Immediate actions

• If symptoms are mild, try taking the tablet with food and avoid spicy/irritating foods; do not stop the drug without consulting the prescribing doctor.
• Avoid nonsteroidal anti-inflammatory drugs (NSAIDs) which can worsen stomach irritation.
• Keep hydrated, rest, and use bland meals to help appetite.
• Contact the prescribing doctor or a gastroenterologist promptly to review the drug and consider alternative treatment or supportive medicines.

⚠️ Warning signs — seek urgent care

• Severe or worsening abdominal pain or high fever.
• Yellowing of skin/eyes or dark urine (possible liver injury).
• Fainting, fainting spells, chest pain or new fast/irregular heartbeat.

🩺 FOLLOW_UP

• When did these symptoms start relative to taking the tablet?
• Is he taking any other medicines or does he have known liver disease or stomach ulcers?

If you want, I can list specific tests the doctor may order (liver tests, electrolytes, ECG).