The Side Effects of the Depo Injection: (Birth Control Shot)
The Side Effects of the Depo Injection remain one of the most searched topics in South Africa’s reproductive health space. This contraceptive, also called the birth control shot or DMPA (Depot Medroxyprogesterone Acetate), is widely used because of its convenience and effectiveness. In South Africa, it is offered free in most public health facilities, making it a popular choice for many women.
Yet, despite its effectiveness, the Depo injection has both common and rare side effects that women should understand. Recent updates from the South African Health Products Regulatory Authority (SAHPRA) and new research published in international journals highlight the importance of transparent, accurate information.
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How the Depo Injection Works
The Depo injection contains a synthetic form of progesterone. Once injected into the muscle or under the skin, it prevents ovulation for 12 weeks. It also thickens cervical mucus, making it harder for sperm to reach an egg.
According to the Centers for Disease Control and Prevention (CDC), the injection is more than 94% effective when used correctly. This makes it one of the most reliable methods of contraception.
Common Side Effects of the Depo Injection
The most frequent side effects involve changes to menstrual bleeding patterns. Many women experience irregular bleeding, spotting, or even no periods (amenorrhea).
The CDC states:
“Amenorrhea and spotting or light bleeding are common… heavy or prolonged bleeding can occur.”
These side effects usually improve with time. For many women, the convenience of not worrying about daily pills outweighs the initial changes.
Weight Gain and Appetite Changes
One of the most reported concerns is weight gain. Some studies show that women who gain more than 5% of their weight in the first three months are more likely to gain more later.
The CDC notes that early weight gain can be a predictor of longer-term gain. However, not all women experience this, and lifestyle factors such as diet and exercise also play a role.
Impact on Fertility After Stopping the Injection
Unlike other contraceptives, fertility may take longer to return after stopping Depo. Research shows that ovulation usually returns between 15 and 49 weeks after the last injection.
The CDC explains:
“Time to ovulation… with the majority ranging from 15 to 49 weeks from the last injection.”
This delay does not mean infertility, but women planning a pregnancy soon should consider other options.
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Bone Health and Long-Term Use
Long-term use of the Depo injection may reduce bone mineral density. This is more concerning for teenagers and women approaching menopause.
The UK National Health Service (NHS) warns:
“Using the contraceptive injection for more than 1 year can cause your bones to become weaker. Your bones are likely to return to normal after you stop.”
Doctors may recommend monitoring bone health or switching to other contraceptives if long-term use is expected.
Cancer Risks: What the Evidence Says
The link between Depo and cancer risk is still being studied. Evidence suggests a small, reversible increase in the risk of breast and cervical cancer while using the injection.
The NHS notes that this risk decreases after stopping the shot. Importantly, the benefits of preventing unplanned pregnancies often outweigh these risks for most women.
Rare But Serious Side Effect: Meningioma
In January 2025, SAHPRA issued a safety update regarding medroxyprogesterone acetate. This followed a BMJ 2024 study suggesting a small increased risk of meningioma, a rare but usually non-cancerous brain tumour, with prolonged use.
SAHPRA stated:
“The absolute risk… is low. However, product information must include updated warnings on meningioma risk.”
Women using the injection long term should be informed, but the risk remains very rare.
HIV and STI Considerations
The Depo injection does not protect against sexually transmitted infections, including HIV. South Africa, with its high HIV prevalence, requires clear counselling on this point.
The World Health Organization (WHO) emphasises that women at high risk of HIV can still use hormonal contraceptives but should be offered HIV prevention tools such as condoms and pre-exposure prophylaxis (PrEP).
Self-Administration: The New DMPA-SC Option
A newer option, DMPA-SC (subcutaneous Depo), is now available and supported by the South African National Essential Medicines List Committee (NEMLC). Women may even self-inject under guidance, increasing privacy and convenience.
The committee’s March 2025 review concluded:
“NEMLC suggests that either low dose DMPA-SC or intramuscular progestogen injectables may be used.”
This development expands access while still offering the same level of effectiveness.
Managing Side Effects Effectively
Healthcare providers can help manage side effects. For example, non-steroidal anti-inflammatory drugs (NSAIDs) can reduce heavy bleeding. Lifestyle counselling may assist with weight management.
Most importantly, women should not feel alone in dealing with side effects. Regular follow-ups with healthcare providers can ensure that any challenges are addressed quickly.
Balancing Risks and Benefits
Every contraceptive carries some risks. For the Depo injection, the main concerns are bleeding changes, delayed fertility return, bone health, and rare risks such as meningioma.
However, the benefits are significant: highly effective contraception, convenience, and privacy. For many South African women, especially those who cannot access daily pills easily, the Depo injection remains a practical choice.
Expert Advice for South African Women
When choosing contraception, consult a healthcare provider to discuss your health history and family planning goals.
Dr. Jane Harries, a reproductive health researcher at the University of Cape Town, notes:
“Contraceptive choice should always be about balancing benefits and risks. Women need accurate information to make empowered decisions.”
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The Side Effects of the Depo Injection are well-documented and range from common bleeding changes to very rare risks like meningioma. South African women deserve clear, evidence-based information to guide their choices.
With new options like self-administered Depo and updated safety guidance from SAHPRA, it is more important than ever to seek professional advice before deciding.
