Key takeaways

IUDs, including hormonal types like Mirena and non-hormonal copper IUDs, are highly effective birth control methods but have not been substantiated to cause weight gain.
Hormonal IUDs may cause an initial increase in water retention leading to perceived weight gain, but this typically subsides within a few months.
Copper IUDs do not contain hormones and thus do not contribute to weight gain, offering an alternative for those concerned about this side effect.
Lifestyle factors and natural body changes contribute more to weight gain than IUD use, with healthy habits recommended to manage weight.

Like all medications, birth control can have side effects. They’re important to consider when choosing the method that’s right for you. Birth control side effects may include acne, breakthrough bleeding, mood changes, and more. Weight gain is a concern among women choosing birth control, but it’s a common misconception that IUDs cause weight gain. To answer some frequently asked questions about IUD weight gain, we talked to Christina Madison, PharmD, FCCP, BCACP, AAHIVP, founder of The Public Health Pharmacist and clinical researcher of women’s health.

What is an IUD?

An IUD, or intrauterine device, is a small, T-shaped plastic device placed in the uterus to prevent pregnancy. With less than a 1% risk of pregnancy each year, IUDs are the most effective form of birth control available. IUDs are a great choice for those who often forget to take their daily birth control pills. After insertion, an IUD lasts anywhere from three to 12 years. It can be used by women of all ages, according to the CDC. They are also a reversible contraception option, allowing you to go back to regular fertility once your IUD is removed.

There are two types of IUD products: copper and hormonal. While both are effective in preventing pregnancy, there are some key differences to keep in mind.

Copper IUDs

Copper IUDs are hormone-free. They use plastic and copper coils instead of levonorgestrel. Copper is a natural spermicide, killing sperm before it can reach an egg. Copper IUDs, like ParaGard, can be used for up to 12 years.

Hormonal IUDs

Sometimes referred to as intrauterine systems, hormonal IUDs release small amounts of a progestin hormone called levonorgestrel into the uterus, which prevents sperm from reaching and fertilizing an egg. These IUDs can last anywhere from three to eight years.

One of the most common hormonal IUD brands is Mirena, manufactured by Bayer. Mirena prevents pregnancy for up to five years but may remain effective for up to eight years.

The cost of Mirena varies, but Bayer recently reported that 95% of women are covered with little to no out-of-pocket costs. The list price of Mirena is $1,410, which comes out to about $15 per month over eight years. If your insurance doesn’t cover it, there are Mirena coupons available.

Other common brands include Skyla, Liletta, and Kyleena. Each hormonal IUD brand is different, so be sure to consult with your OB-GYN on which is right for you.

What are the side effects of an IUD?

Both hormonal and copper IUDs do much more than just preventing pregnancy. For example, Mirena treats heavy bleeding, which benefits those who experience endometriosis-related pain. ParaGard, the copper IUD, is also used as an emergency contraceptive since it begins working immediately.

Side effects of intrauterine dosage forms, like the Mirena IUD, are typically less severe than those seen with oral contraceptives, according to Dr. Madison.

While IUDs are 99% effective, there are some common side effects that include:

Cramping and back pain after placement
Irregular bleeding and spotting
Irregular periods, which may become lighter or even stop
Ovarian cysts, which usually disappear
Heavy menstrual bleeding or longer periods with copper IUDs

Rare, but serious, side effects of IUDs include:

Potential risk of pelvic infection within 20 days after insertion
The IUD slipping or moving, which will need to be taken out by a professional
Expulsion of the device from the uterus

Mirena side effects

Possible side effects of IUDs vary from patient to patient. Side effects may also depend on the type of IUD used. The Mirena IUD may have additional, hormone-based side effects, such as:

Headaches
Acne
Breast tenderness
Mood swings
Nausea
Fatigue

Since Mirena and other hormonal IUDs use the progestin hormone instead of estrogen, some patients may experience weight gain or hair loss due to lower estrogen levels. However, these side effects are uncommon and may be related to a number of other health issues, such as stress or other illnesses.

“Benefits of using these highly effective and long-acting products outweigh the risk of potential side effects,” says Dr. Madison, but make sure to consult with your doctor to determine if an IUD is the right option for you.

RELATED: Mirena alternatives

IUD weight gain

The majority of IUD users do not experience weight gain. Copper, non-hormonal IUDs do not cause weight gain, whereas about 5% of patients using hormonal IUDs report weight gain. Since Mirena is a hormonal IUD, Mirena weight gain is possible, but unlikely.

“The perception of weight gain from these products is widely thought of, but has not been substantiated,” says Dr. Madison. “There was no difference in body weight or composition seen among [IUD] products after 12 months of continuous use.” While you may have some weight gain after getting your IUD, it should subside.

Weight gain can happen with hormonal IUDs due to the hormone, progestin. Any IUD weight gain is likely not an increase in body fat, but instead an increase in water retention. The hormone progestin may increase water retention that causes bloating, typically adding about five pounds. The amount of weight gained will vary from patient to patient, but any water retention will likely go down three months post-insertion.

It’s important to know that gaining any weight post-insertion is likely due to the patient’s lifestyle as opposed to the IUD itself. Many American women naturally gain two pounds each year, entirely unrelated to any hormonal contraceptives, according to Yale Medicine.

Consider making some lifestyle changes to avoid weight gain after getting an IUD. Exercising regularly, eating a balanced diet, and other common healthy habits should minimize the chances of any weight change after getting an IUD.

Should bloating not subside three months after IUD insertion, consider speaking with a healthcare professional about other options. Copper IUDs, like Paragard, have not been linked to weight gain, making them a great alternative.

What birth control doesn’t cause weight gain?

Should an IUD prove to be not the best birth control method for you, there are plenty of other contraceptive options to consider. Consult your healthcare provider about what would work best for you. Some common birth control options include:

Birth control pills
Xulane patches
Birth control injections, like Depo-Provera
Contraceptive implants, like Nexplanon
Vaginal rings, like NuvaRing

Hormonal birth control gets a bad reputation for causing weight gain. However, weight gain is not a side effect of most birth control methods. Any weight gain reported while taking birth control is likely natural, like aging or your metabolism slowing down.

Only one form of birth control has been linked to weight gain, and that’s the injection Depo-Provera. If you’re looking to avoid weight gain, stay away from injectable contraceptives. These injectables have been shown to activate signals that control hunger, resulting in weight gain in some patients.

As you consider other birth control options, keep in mind that some, like the pill, injections, patches, and vaginal rings, have 10% yearly failure rates due to human error.

“Choosing the best contraceptive product is very individualized,” says Dr. Madison, so make sure to speak openly and honestly with your gynecologist about which birth control method is right for you.

IUD weight gain FAQs

Does Mirena cause weight gain?

Mirena has not been shown to cause weight gain. Less than 10% of Mirena users experienced weight gain in its manufacturer clinical trials. There was not enough evidence to show that these participants’ weight gain was caused by Mirena. However, it is possible to initially gain a few pounds due to an increase in water retention, which should subside after a few months.

What should I do if I gain weight on Kyleena?

If you experience weight gain with Kyleena, try to find the cause of the weight gain. Was there a recent change in your life that may be causing it? There is a multitude of reasons that someone can gain weight. Kyleena does not have evidence of weight gain by itself, but an initial weight gain of a few pounds due to water retention should not be alarming. Practicing a healthy lifestyle with a balanced diet and regular exercise can help prevent weight gain. However, if you experience unexplained weight gain, talk to your healthcare provider because it could be caused by another medical condition.

Why do people gain weight with IUDs?

People can gain weight with IUDs due to water retention. This usually goes away within a few months of getting an IUD inserted. Generally, IUDs do not show an increase in actual weight or body fat.

Can a copper IUD make you gain weight?

Studies have shown that Copper IUDs do not cause weight gain. This is because they do not have progestin, the hormone present in hormonal IUDs that causes water retention. If you gain weight unexplainably with a copper IUD, speak to a healthcare provider. It could be caused by an underlying condition.