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Phentermine and Plan b drug interactions - a phase IV clinical study of FDA data

Summary:

Drug interactions are reported among people who take Phentermine (phentermine hydrochloride) and Plan b (levonorgestrel). Common drug interactions include vaginal haemorrhage among females.

The phase IV clinical study analyzes what interactions people have when they take Phentermine and Plan b. It is created by eHealthMe based on reports of 28 people who take the same drugs from the FDA, and is updated regularly.

What is Phentermine?

Phentermine has active ingredients of phentermine hydrochloride. It is often used in weight loss. eHealthMe is studying from 19,870 Phentermine users. Check the latest studies of Phentermine.

What is Plan b?

Plan b has active ingredients of levonorgestrel. It is often used in birth control. eHealthMe is studying from 38,623 Plan b users. Check the latest studies of Plan b.

On Jul, 16, 2026

28 people who take Phentermine and Plan b together, and have interactions are studied.

Phentermine and Plan b drug interactions.

What are the common drug interactions of Phentermine and Plan B, by gender? *:

female:

  1. Vaginal haemorrhage (vaginal bleeding)
  2. Nausea (feeling of having an urge to vomit)
  3. Drug exposure during pregnancy
  4. Muscle spasms (muscle contraction)
  5. Pollakiuria (abnormally frequent passage of relatively small quantities or urine)
  6. Oligomenorrhoea (infrequent (or, in occasional usage, very light) menstruation)
  7. Abortion spontaneous (naturally occurring miscarriage)
  8. Breast swelling
  9. Breast tenderness
  10. Drug ineffective

male:

n/a

What are the common drug interactions of Phentermine and Plan B, by age (0-1 to 60+)? *:

0-1:

n/a

2-9:

n/a

10-19:

  1. Dysmenorrhoea (painful menstruation)
  2. Vaginal discharge

20-29:

  1. Nausea (feeling of having an urge to vomit)
  2. Menstruation delayed (late menstruation cycle)
  3. Vaginal haemorrhage (vaginal bleeding)
  4. Menstruation irregular
  5. Abdominal distension
  6. Abdominal pain
  7. Breast swelling
  8. Diarrhoea
  9. Dizziness
  10. Dysmenorrhoea (painful menstruation)

30-39:

  1. Abdominal distension
  2. Abdominal pain
  3. Abortion spontaneous (naturally occurring miscarriage)
  4. Breast tenderness
  5. Diarrhoea
  6. Dizziness
  7. Drug ineffective
  8. Ectopic pregnancy (a pregnancy in which the foetus develops outside the uterus, typically in a fallopian tube)
  9. Flatulence (flatus expelled through the anus)
  10. Headache (pain in head)

40-49:

  1. Vaginal haemorrhage (vaginal bleeding)
  2. Dysmenorrhoea (painful menstruation)
  3. Menstruation irregular
  4. Muscle spasms (muscle contraction)

50-59:

n/a

60+:

n/a

What are the existing conditions these people have? *

  1. Weight Decreased: 9 people, 32.14%
  2. Stress And Anxiety: 3 people, 10.71%
  3. Appetite - Decreased (decreased appetite occurs when you have a reduced desire to eat): 3 people, 10.71%

* Approximation only. Some reports may have incomplete information.

Do you take Phentermine and Plan b?

- Personalize this study to your gender, age, symptoms and drugs
- Predict drug outcomes for up to one year with AI
- Get an AI agent to monitor your drugs continuously

Related studies:

Effectiveness of, side effects of, and alternative drugs to the 2 drugs:

Browse all drug interactions of Phentermine and Plan b:

a b c d e f g h i j k l m n o p q r s t u v w x y z

Sub-studies by gender and age:

Female: 0-1 2-9 10-19 20-29 30-39 40-49 50-59 60+

Male: 0-1 2-9 10-19 20-29 30-39 40-49 50-59 60+

Browse all side effects of Phentermine:

a b c d e f g h i j k l m n o p q r s t u v w x y z

Browse all side effects of Plan b:

a b c d e f g h i j k l m n o p q r s t u v w x y z

Browse all interactions between Phentermine and drugs from A to Z:

a b c d e f g h i j k l m n o p q r s t u v w x y z

Browse all interactions between Plan b and drugs from A to Z:

a b c d e f g h i j k l m n o p q r s t u v w x y z

How the study uses the data?

The study uses data from the FDA. It is based on phentermine hydrochloride and levonorgestrel (the active ingredients of Phentermine and Plan b, respectively), and Phentermine and Plan b (the brand names). Other drugs that have the same active ingredients (e.g. generic drugs) are not considered. Dosage of drugs is not considered in the study.

How to use the study?

DO NOT STOP MEDICATIONS without first consulting your doctor. If there are any serious or long term adverse effects discovered in the study, discuss the study with your doctor to ensure that proper medication management will be in place if applicable.

Who is eHealthMe?

With medical big data and proven AI/ML algorithms, eHealthMe provides a platform for everyone to run phase IV clinical trials. We study millions of patients and 5,000 more each day. Results of our real-world drug study have been referenced on 800+ peer-reviewed medical publications, including The Lancet, Mayo Clinic Proceedings, and Nature. Our analysis results are available to researchers, health care professionals, patients (testimonials), and software developers (open API).

WARNING, DISCLAIMER, USE FOR PUBLICATION

WARNING: Please DO NOT STOP MEDICATIONS without first consulting a physician since doing so could be hazardous to your health.

DISCLAIMER: All material available on eHealthMe.com is for informational purposes only, and is not a substitute for medical advice, diagnosis, or treatment provided by a qualified healthcare provider. All information is observation-only. Our phase IV clinical studies alone cannot establish cause-effect relationship. Different individuals may respond to medication in different ways. Every effort has been made to ensure that all information is accurate, up-to-date, and complete, but no guarantee is made to that effect. The use of the eHealthMe site and its content is at your own risk.

If you use this eHealthMe study on publication, please acknowledge it with a citation: study title, URL, accessed date.

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