In brief: Tight socks. Tight socks won't cause blood clots. In fact, special compression stockings are used in older people to help prevent blood clots from forming in the legs. However, tight socks are bad for circulation in people of any age. You should buy socks and shoes that are comfortable and that fit well, but are not too tight. In brief: Tight socks. Tight socks won't cause blood clots. In fact, special compression stockings are used in older people to help prevent blood clots from forming in the legs.