Common Hot flashes, Weakness, Increased sweating, Back pain, Paresthesia (tingling or pricking sensation), Decreased libido, Impotence.

Expert advice for Decapeptyl Injection

Stop the treatment around physiologic age of puberty (girls: not more than 12 years of bone maturation, boys: not more than 13 to 14 years of bone maturation).
Inform your doctor immediately if you are in a depressive mood or have any depression issues while on therapy with triptorelin.
For puberty treatment, inform the doctor if the child has a progressive brain tumor. 
Girls suffering from early puberty may have some vaginal bleeding after the first treatment.
Males on treatment for prostate cancer may experience urinary blockage, which will be managed by some medication prescribed by your doctor.
Women on treatment for endometriosis may have some vaginal bleeding initially which will eventually resolve. Periods will start normally 5 months post therapy. 
Two forms of contraception must be practiced during therapy: one may be the pill and the other should be a physical barrier like a condom or diaphragm.
You may be at higher risk of developing osteoporosis (thin and weak bones) if you are an alcoholic or a smoker or have a family history of osteoporosis or have poor diet habits or are taking any anti-convulsants/ corticosteroids.
Inform the doctor if you have diabetes or a history of heart problems.
Men should inform the doctor if there is blood in urine, pain or weakness or numbness or tingling in the feet.
Women on therapy should inform the doctor if they are on some therapy which increases prolactin levels.
Do not drive or use heavy machinery post taking this medication as it might cause dizziness, drowsiness or blurred vision.

Q. Is Decapeptyl chemotherapy?
Decapeptyl is a hormone therapy which is also used in the treatment of locally advanced non-metastatic prostate cancer in men

Q. What is Decapeptyl palmoate or Decapeptyl acetate?
Decapeptyl palmoate or acetate is a salt form of Decapeptyl used for the same purposes

Q. How long does Decapeptyl stay in the system?
Decapeptyl stays in circulating blood at very low levels for upto 90 days.