Greetings.
Tretiva has an active ingredient called isotretinoin. This is one of the best medication for acne and that is the reason your dermatologist has suggested you the same. It is very occasional to see hair fall on isotretinoin. Your dermatologist may reduce the dose of tretiva or suggest some medication to improve the ongoing hair loss.
Next Steps
Start on biotin supplements and food rich in iron content.
Health Tips
You can consult me online for personal recommendations.