This is a common question. The answer is NO.
If seamlessly applied, with conservative weight and length its safe to continue your fills without concern. If you have opted for long and thick extensions its best to choose the lighter ones for a while and go for the bolder look on occasion.
Use a growth/conditioning serum like RapidLash all year round to keep your natural lashes strong.
Follow all instructions given to you regarding the care of the extensions.
Choose your therapist wisely, badly applied lashes will destroy them and pull out your lashes and possibly irreparably damage the natural lash.