generally, after the first injection, the stovepipe needle can be used for a second time at intervals of about 3 months to achieve a better stovepipe effect, and the stovepipe effect can be maintained for a longer time. However, it should be noted that the effect of stovepipe needle injection is different because of everyone's different physique. If you have a good stovepipe effect after one injection, you can inject it again at a long interval. If the stovepipe effect is not good after one injection, you need to inject it several times. Generally speaking, the side effects can be effectively avoided by controlling the dosage and concentration of stovepipe needles, but how to use stovepipe needles excessively or inject stovepipe needles too frequently can easily cause side effects to human body. When injecting stovepipe needles, you must not inject them many times and frequently in a short time in order to pursue the effect.