The 2-month contraceptive injection, a progestogen-only method, can cause a range of side effects. Common side effects include changes to your periods—such as periods stopping, becoming irregular, or lasting longer—especially within the first year of use[1]. About half of users may stop getting their period while using the injection, which is considered safe[3]. Some people might experience heavier or longer periods, though this is less common[4].
Other frequent side effects are:
- Weight gain, typically 1–2 kg per year[1][4]
- Pain, bruising, or a small lump at the injection site[1][6]
- Headaches and dizziness[1][5][6]
- Bloating and abdominal discomfort[2][6][7]
- Reduced sex drive (libido)[1][2][6]
- Mood changes, irritability, or depression[1][2][5][6]
- Hot flushes and flushing sensations[1][5]
- Acne and skin changes[1][5]
- Sore or tender breasts[3]
- Nausea[3]
- Occasional dizziness, nervousness, weakness, or tiredness[4][6]
Most side effects, particularly those related to hormonal adjustment (like headaches, bloating or mild mood changes), usually improve or resolve after the first few months[3][6]. However, persistent or bothersome symptoms should be discussed with a healthcare provider[1][6].
Long-term or more serious risks include decreased bone density with prolonged use (over one year), as the injection may reduce estrogen levels essential for bone health. This bone loss is often reversible after stopping, but long-term use is associated with a higher risk and should be discussed, especially for those at risk of osteoporosis[1][7]. Rarely, extended use increases the risk of meningioma (a type of brain tumor) and may slightly elevate the risk of certain cancers, but this risk is very low and diminishes after discontinuation[1][7].
Other rare side effects or reactions may include allergic responses, fluid retention, or a permanent small skin dent at the injection site[2][3].
If you experience troublesome side effects, heavy or prolonged bleeding, signs of an allergic reaction, or any symptoms that concern you, consult your healthcare provider promptly[1][6].
References
- [1] Side effects and risks of the contraceptive injection – NHS
- [2] Depo Provera | The Royal Women’s Hospital
- [3] Are there birth control shot side effects? – Planned Parenthood
- [4] Contraceptive injection – 1 Month and 3 Month Types
- [5] Side-effects – Contraceptive Injection – SH:24
- [6] Depo-Provera (birth control shot) – Mayo Clinic
- [7] Long-Term Side Effects of Depo-Provera Shots [2025] – Sokolove Law