--- title: "Phentermine Side Effects in Females: What to Watch Out for as a Woman" description: "Wondering how phentermine might affect your period, hormones, or sex drive? Learn more about common and long-term side effects it may have in women." authors: - "Kimberly Rath" reviewers: - "Dr. Michael Chichak" date: "2025-05-30 14:33:22" canonical: "https://medvidi.com/blog/phentermine-side-effects-in-females" categories: - "Medications" - "Weight Loss" --- # Phentermine Side Effects in Females The medications listed on this website are provided for informational purposes only.Their inclusion does not guarantee they will be prescribed to any individual, as treatment decisions are ultimately at the discretion of healthcare providers. Healthcare providers may prescribe other medications or recommend non-pharmacological treatment based on the patient’s unique health circumstances and needs. [Read more](#) Phentermine is a controlled substance Phentermine is a Schedule IV controlled substance, which means that it has a risk of abuse and dependence. Specific federal and state laws limit the amount of this medication that can be prescribed or dispensed within a certain period of time. ### Highlights - Phentermine is an FDA-approved prescription medication used short-term for weight loss. It should be used in combination with lifestyle changes, such as a healthy diet and exercise.- Phentermine can cause side effects such as dry mouth, insomnia, and increased heart rate. Women may also experience menstrual irregularities, including delayed or missed periods.- Phentermine is not recommended during pregnancy or breastfeeding due to potential risks to the fetus and infant. Phentermine is a medication that is used short-term to help with weight loss, especially for people who haven’t been able to lose weight with diet and exercise alone. But if you’re a woman considering this medication, it’s important to know how it may affect your body differently, especially when it comes to your menstrual cycle, hormone balance, and sexual health. Get a personalized weight loss pan online, including medication prescription if deemed appropriate. [ ** Book an appointment ](https://join.medvidi.com/signup) ## What Is Phentermine? Phentermine is a prescription medication that helps suppress appetite, making eating less and losing weight easier. It is available in both phentermine oral tablets and extended-release capsules. Because phentermine is a stimulant and can be habit-forming, it’s classified as a [Schedule IV controlled substance](https://www.sciencedirect.com/topics/pharmacology-toxicology-and-pharmaceutical-science/phentermine) and is only meant for short-term use — up to 12 weeks. Common brand names include Adipex-P and Lomaira, and a drug combination of phentermine with topiramate is also available under the brand name [Qsymia](https://medvidi.com/blog/qsymia-for-weight-loss). Phentermine works by stimulating the central nervous system (CNS), which is responsible for alertness, energy levels, and appetite control. It increases the levels of certain brain chemicals (norepinephrine, dopamine, and serotonin) that reduce appetite and may help increase metabolism. As a result, many people find they feel fuller for longer and are able to reduce their calorie intake more easily. ## Common Phentermine Side Effects While phentermine can aid in weight loss, it may cause [side effects](https://www.accessdata.fda.gov/drugsatfda_docs/label/2012/085128s065lbl.pdf), including: - Dizziness- Dry mouth- Headache- Restlessness- Unpleasant taste- Trouble sleeping- Constipation or diarrhea- Sexual side effects- Increased blood pressure- Increased heart rate ## Female-Specific Side Effects Women may be more sensitive to the effects of phentermine due to unique physiological and hormonal factors, including monthly hormone fluctuations, changes in body fat distribution, and a generally slower metabolism. While phentermine doesn’t directly affect hormone levels, it can indirectly disrupt hormonal balance through stress responses, weight loss, and changes in brain chemistry, all of which can affect menstrual cycles and reproductive hormones. Sexual side effects seen in women are different from those in men. While men may experience erectile dysfunction, phentermine side effects in females may include reduced arousal, delayed orgasm, or discomfort during sex. ### Сan Phentermine Affect Your Period? Yes, many women report changes in period frequency, flow, and timing while taking phentermine. These include lighter or heavier periods, late or missed periods, or irregular cycles. These changes are usually due to weight loss and hormonal shifts. ### Does Phentermine Affect Birth Control? Phentermine does not reduce the effectiveness of birth control pills in preventing pregnancy. However, it can cause breakthrough bleeding or spotting in women who take oral contraceptives. ### Does Phentermine Affect Female Fertility? While not directly linked to infertility, phentermine can influence hormonal balance and menstrual cycles, which may affect fertility. ### Does Phentermine Increase Sex Drive in Females? Some women notice an increase in libido, while others may experience a decrease or no change at all. Women may also find it harder to become aroused, reach orgasm more slowly, or experience pain during sex. These changes are likely related to phentermine’s stimulant effects, shifts in energy and mood, and hormonal fluctuations from weight loss. ### Does Phentermine Cause Yeast Infections? Yeast infections are not a known side effect of phentermine. However, a common side effect of phentermine is [dry mouth](https://www.mayoclinic.org/diseases-conditions/dry-mouth/symptoms-causes/syc-20356048#:~:text=Not%20having%20enough%20saliva%20and,mouth%2C%20also%20known%20as%20thrush.), which can increase the risk of a yeast infection in the mouth, known as oral thrush. ### Why Does Phentermine Cause Breast Pain? Breast tenderness or pain may be related to the hormonal changes that can occur with rapid weight loss or changes in body composition. See a healthcare provider experienced in weight loss treatment and get all your questions answered online. [ ** Book an appointment ](https://join.medvidi.com/signup) ## Phentermine Use in Special Female Populations ### Pregnancy Phentermine should not be used during pregnancy, as weight loss during pregnancy isn’t recommended. In addition, phentermine has been linked to harmful effects on the unborn baby. If you’re pregnant or planning to become pregnant, let your healthcare provider know. Phentermine isn’t recommended for pregnant women, so it’s best to stop taking it before trying to conceive. ### Breastfeeding It [isn’t known](https://www.ncbi.nlm.nih.gov/books/NBK582102/) if phentermine passes into breast milk. However, other stimulant medications are known to pass into breast milk. Because of potential risks to the infant, such as irritability, sleep disturbances, feeding problems, and potentially more serious risks like changes in blood pressure and heart rate, phentermine use is not recommended while breastfeeding. ### Menopause Menopause often comes with hormonal changes that can cause weight gain or make weight loss more difficult. Among menopausal women, it’s estimated that [over 43%](https://pmc.ncbi.nlm.nih.gov/articles/PMC8373626/) are obese, and many women inquire about the use of weight loss medications. While phentermine may help, it should be used with caution. During menopause, the natural decline in estrogen levels increases a woman’s risk of cardiovascular disease. Because of this, menopausal women should use phentermine with caution. Women with a history of heart problems, arrhythmias, or other risk factors such as heart disease should avoid phentermine. ## Serious Side Effects and Long-Term Risks The long-term use of phentermine increases the risk of side effects. Although serious side effects are rare, some could be life-threatening if not treated right away. They may include: - **Heart problems**, including increased heart rate, heart palpitations, and even heart attacks. - **Valvular heart disease**, which causes the heart’s valves (that control blood flow through the heart) to become damaged or not function properly. - **Primary pulmonary hypertension** (high blood pressure in the lungs), a rare but serious condition and may cause symptoms such as chest pain, shortness of breath, dizziness, and swelling in the arms or legs. - **Severe mood disturbances**, including depression or irritability. These effects occur more frequently in people taking high doses or misusing phentermine. - **Withdrawal symptoms** if a high dose of phentermine is taken for a prolonged period of time. Serious allergic reactions are possible from taking phentermine. Signs of an allergic reaction may include rash, itching, swelling (especially of the face, tongue, or throat), severe dizziness, or trouble breathing. If you experience any serious side effects during treatment with phentermine, seek medical attention immediately. ## How to Minimize Side Effects To reduce the risk of adverse effects while taking phentermine, it’s important to take it exactly as your healthcare professional prescribes. Starting with the lowest effective dose can help, as higher doses are more likely to cause issues like dry mouth, anxiety, trouble sleeping, and stomach pain. "One way to help avoid side effects with medication such as this is to make sure that you take the medication around the same time each day. With phentermine, it is important to take it in the morning. Some patients will experience side effects when taking the medication too late in the day or at various times of the day." * [**Dr. Michael Chichak, MD**](/team/dr-michael-chichak/) Medical provider at MEDvidi Dry mouth and trouble sleeping are among the [most commonly](https://pmc.ncbi.nlm.nih.gov/articles/PMC3791337/) reported side effects of phentermine. To minimize dry mouth, drink plenty of fluids to stay well hydrated. To reduce the risk of insomnia, taking phentermine once daily in the morning is recommended — this gives your body more time to process the medication and minimize trouble sleeping. Phentermine is meant for short-term use of up to 12 weeks — taking it for longer can cause an increased risk of serious side effects. Regular check-ins with your healthcare provider are important so they can monitor your blood pressure, heart rate, and determine [how well phentermine is working for you](https://medvidi.com/blog/do-weight-loss-pills-work). If you have diabetes, your healthcare provider will also monitor your blood sugar more closely. In addition to taking phentermine, you should continue to make healthy lifestyle choices, such as eating nutritious foods, staying physically active, getting enough rest, and finding ways to manage stress. Get ongoing support for your weight loss journey online at MEDvidi. Book an appointment today. [ * Get started ](https://join.medvidi.com/signup) ## Interactions and Contraindications Before taking phentermine, talk with your healthcare provider about other medications you’re currently using. Some medications are known to cause [drug interactions](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=06573bd8-67b4-4478-8325-aa6be25787cb). - Medicines known as monoamine oxidase inhibitors (MAOIs), such as phenelzine (Nardil), selegiline (Emsam), and tranylcypromine (Parnate), may cause a dangerously high blood pressure if taken with phentermine. - Some common antidepressants like citalopram (Celexa), escitalopram (Lexapro), fluoxetine (Prozac), and sertraline (Zoloft) may increase the risk of serotonin syndrome. - Blood pressure medications may not work as well. It’s also not recommended to combine phentermine with other weight loss medications, dietary supplements, or stimulants without first talking to your healthcare provider. People with certain medical conditions shouldn’t take phentermine, including those with: - heart disease, such as coronary artery disease or congestive heart failure; - uncontrolled high blood pressure; - an overactive thyroid gland; - glaucoma; - a history of heart attack or stroke; - a history of drug abuse or dependence. "With a medication such as phentermine, some states have specific guidelines as to how long it can be taken in conjunction with certain health metrics. Also, certain health conditions would contraindicate the use of phentermine. So, remember to discuss this with your healthcare provider to make sure that this is the right medication for you and your treatment plan is catered to your unique situation." ![Dr. Michael Chichak](https://medvidi.com/wp-content/uploads/2024/10/Dr.-Michael-Chichak-MD.png) [**Dr. Michael Chichak, MD**](/team/dr-michael-chichak/) Medical provider at MEDvidi ## Phentermine Alternatives If phentermine isn’t right for you, there are other FDA-approved [weight loss medications](https://medvidi.com/blog/weight-loss-prescription-medications), including: - **Orlistat (Xenical, Alli): **A tablet taken by mouth 3 times a day. It works in your digestive system to block fat absorption from food. It can be purchased over-the-counter (Alli) or by prescription (Xenical). It may cause gastrointestinal side effects like oily stools. - **Liraglutide (Saxenda):** A once-daily injection that helps you feel full longer and eat less. It mimics a natural hormone that controls appetite.  - [**Semaglutide**](https://medvidi.com/blog/how-to-get-semaglutide)** (**[**Wegovy**](https://medvidi.com/blog/phentermine-vs-wegovy)**):** A once-weekly injectable medication that reduces appetite. It is also used to control blood sugar in people with diabetes type 2 under the brand name [Ozempic](https://medvidi.com/blog/phentermine-vs-ozempic). - **Naltrexone-bupropion (Contrave):** A once-daily combination medication that helps reduce hunger and cravings. It may also improve mood and energy. - **Tirzepatide (**[**Zepbound**](https://medvidi.com/blog/how-to-get-zepbound-prescription-online)**): **A newer, once-weekly injectable medication targeting two hunger-related hormones (GLP-1 and GIP). ## Final Thoughts When used properly alongside a reduced-calorie diet and regular exercise program, phentermine can be a helpful short-term weight loss aid. However, it also carries potential side effects, particularly for women. Understanding how it may affect your hormones, menstrual cycle, and heart health can help you make more informed decisions. Talk with a licensed healthcare professional from MEDvidi to determine if [phentermine treatment](https://medvidi.com/blog/how-to-get-a-phentermine-prescription-online) is a good option for you: book an appointment to have an [online weight loss consultation](https://medvidi.com/services/weight-loss-treatment/). ## Phentermine Side Effects in Females FAQs ### How much weight can a woman lose on phentermine? Research shows that women lose an average of [5% to 10%](https://pmc.ncbi.nlm.nih.gov/articles/PMC3791337/) of their initial body weight over 12 weeks. The amount of weight you lose while taking phentermine mostly [depends](https://pmc.ncbi.nlm.nih.gov/articles/PMC3791337/) on how much extra weight you have and how well you’re able to make healthy changes to your eating and exercise habits during treatment. ### Is anger a side effect of phentermine in females? Mood changes, including irritability and anger, can occur in some individuals. ### Does phentermine interact with progesterone? There are no known significant interactions, but both can influence hormonal balance, so it’s important to talk with your doctor before combining them. ### Can you get pregnant on phentermine? Yes. Phentermine does not prevent pregnancy. Effective contraception is advised while using phentermine. ### How long should you stop taking phentermine before getting pregnant? It is recommended to discontinue phentermine at least several weeks before attempting to conceive.