Can Phentermine Cause Bleeding Between Periods Can Phentermine Cause Bleeding

Summary: Phentermine is a prescription medication used for weight loss. Some women who take it have reported experiencing bleeding between periods. In this article, we will explore if phentermine can cause bleeding between periods, what are the possible causes, and what should you do if you experience this side effect.

1. What is Phentermine?

Phentermine is a stimulant drug that works by suppressing appetite. It is approved by the FDA for short-term use (up to 12 weeks) as an aid to weight loss in obese individuals. The medication is usually prescribed along with a low-calorie diet, exercise, and behavior therapy. Phentermine is available in different forms, such as tablets, capsules, and extended-release capsules.

Phentermine is classified as a controlled substance due to its potential for abuse and dependence. It should not be taken by people with a history of drug or alcohol abuse, uncontrolled high blood pressure, heart disease, hyperthyroidism, or glaucoma. It can also interact with other medications, such as MAO inhibitors, antidepressants, and benzodiazepines.

Phentermine can cause several side effects, including dry mouth, constipation, diarrhea, headache, dizziness, insomnia, increased heart rate, high blood pressure, and mood changes. Less commonly, it can cause more serious side effects, such as pulmonary hypertension, valvular heart disease, and psychotic reactions.

2. Can Phentermine Cause Bleeding Between Periods?

Bleeding between periods, also known as intermenstrual bleeding, is a common gynecological problem that can have various causes. It can occur for many reasons, such as hormonal imbalances, infection, inflammation, polyps, fibroids, endometriosis, cancer, or pregnancy. Therefore, it is important to see a healthcare provider if you experience this symptom, especially if it persists or is severe.

There is limited research available on the association between phentermine use and intermenstrual bleeding. However, there are some case reports and anecdotal evidence suggesting that phentermine may be a possible cause of this side effect. The mechanism by which phentermine could induce bleeding between periods is not clear, but it may be related to alterations in hormonal levels or blood vessels.

Additionally, phentermine can indirectly affect the menstrual cycle by reducing the body’s energy stores, such as fat, which can lead to changes in hormone production and metabolism. This effect may be more pronounced in women who have pre-existing hormonal imbalances or disorders, such as polycystic ovary syndrome (PCOS).

3. What Should You Do If You Experience Bleeding Between Periods While Taking Phentermine?

If you experience bleeding between periods while taking phentermine, you should consult your healthcare provider. It is important to rule out other possible causes of this symptom and to evaluate if the medication is still appropriate for you. Your provider may ask you about your medical history, menstrual cycle patterns, sexual activity, and other symptoms you may have. They may also perform a pelvic exam, blood tests, ultrasounds, or other imaging tests to assess the pelvic organs and hormonal levels.

Your provider may recommend stopping or adjusting your phentermine treatment if they suspect it is causing the bleeding. Alternatively, they may refer you to a gynecologist or endocrinologist for further evaluation and management. Depending on the underlying cause of your intermenstrual bleeding, your provider may prescribe other medications, such as contraceptives, anti-inflammatory drugs, antibiotics, or surgery. They may also suggest lifestyle modifications, such as weight loss, exercise, or stress reduction, to improve your overall health and well-being.

It is crucial to follow your provider’s instructions and to attend any follow-up appointments to monitor your bleeding and treatment progress.

4. How Can You Prevent Bleeding Between Periods While Taking Phentermine?

There is no foolproof way to prevent bleeding between periods, but there are some measures you can take to reduce your risk. First, it is important to take phentermine as directed by your healthcare provider. Do not exceed the recommended dose or duration, and do not share the medication with others. Follow a healthy diet and exercise plan, and avoid smoking and alcohol consumption. Monitor your menstrual cycle regularly and report any changes or abnormalities to your provider. Use reliable contraception if sexually active to prevent unintended pregnancy and sexually transmitted infections.

If you have pre-existing hormonal imbalances or gynecological disorders, such as PCOS, discuss with your provider how phentermine may affect your condition and if there are alternative weight loss strategies that may be more suitable for you.

If you experience side effects from phentermine, including bleeding between periods, it is important to report them to your healthcare provider as soon as possible.


Phentermine is a weight loss medication that can have various side effects, including bleeding between periods. While the exact prevalence and mechanism of this side effect are not yet clear, it is important to be aware of the possibility and to seek medical advice if you experience it. If you take phentermine, follow your provider’s instructions, and monitor your menstrual cycle and general health regularly. Remember that intermenstrual bleeding can have many causes, and it is important to identify and address the underlying one to prevent complications and improve your quality of life.

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