Hucog-5000 contains a hormone called human chorionic gonadotrophin, which is often used in fertility treatment. After taking this injection, some people may experience mild side effects because the body is adjusting to hormonal changes. Leg pain may happen due to temporary water retention, mild muscle cramps, or a general feeling of heaviness in the body. Sometimes, hormonal stimulation can make muscles and joints a bit more sensitive or slightly affect blood flow, which may contribute to discomfort. If you are using this injection as part of fertility treatment, the ovaries can become more active, and this may cause some lower abdominal discomfort that can sometimes be felt in the legs as well. However, it is also important to remember that leg pain may not always be linked to the injection and could also be due to common factors such as muscle strain, dehydration, vitamin deficiencies, or prolonged standing. In most cases, the pain is mild and settles on its own. However, you should see a doctor urgently if the pain is severe, occurs in only one leg, or is accompanied by swelling, redness, chest pain, or breathlessness.