Does Benadryl (Diphenhydramine) Affect Birth Control Pills?

In our latest question and answer, our pharmacist discusses if it is safe to take Bendaryl with birth control pills.


Does diphenhydramine affect birth control? Does it make them less effective?

Asked by Jeka On Sep 10, 2022

Answered by
Medical Content Reviewed By HelloPharmacist Staff

Published Sep 10, 2022
Last updated Dec 06, 2023

Key points

  • There is no known drug interaction between Benadryl (diphenhydramine) and birth control pills.


There are no known interactions between oral contraceptives (i.e. 'birth control pills') and Benadryl (diphenhydramine). They are considered safe to take together.

Below is some additional information regarding Benadryl and birth control products.

What Is Benadryl?

Benadryl (diphenhydramine) is a first generation, sedating antihistamine (H1-blocker) of the ethanolamine class. It is available in oral, topical, and parenteral product forms.

Benadryl is well known to cause significant sedation in most individuals and is commonly used in night-time sleep aids. Benadryl also has potent "drying" effects in most patients, which is why it causes dry mouth, dry eyes, and constipation.

The onset of action of Benadryl is around 15-30 minutes after taking it by mouth, with peak effects occurring 1 to 3 hours later. The duration of action is around 4 to 6 hours, with this being prolonged in the elderly and in those with liver disease.

What Are Birth Control Pills?

Birth control pills are available as:

  • Progestin-only pills (i.e. 'mini-pills)
  • Combination hormone pill (which contains both a progestin and an estrogen)

Birth control pills are most often used to prevent pregnancy but have a variety of other indications including:

  • Acne
  • Dysmenorrhea (painful menstruation)
  • Amenorrhea
  • PCOS (Polycystic ovary syndrome)
  • Endometriosis

Birth control pills do not prevent sexually transmitted infections (STIs).

Birth control pills mainly work by preventing ovulation. Secondarily, they also induce changes to the cervical mucus lining of the uterus, which reduces the chances of fertilization.

Potential side effects of birth control pills include:

  • Nausea
  • Cramping
  • Bloating
  • Vomiting
  • Weight gain
  • Breast tenderness
  • Headache
  • Spotting and/or breakthrough bleeding

Final Words

Thanks for your question! Reach back out anytime.


  • Contraception, CDC
  • Diphenhydramine Monograph, FDA

About the Pharmacist

Dr. Brian Staiger, PharmD

Dr. Brian has been practicing pharmacy for over 13 years and has wide-ranging experiences in many different areas of the profession. From retail, clinical, program development, and administrative responsibilities, he's your knowledgeable and go-to source for all your pharmacy and medication-related questions! Dr. Brian Staiger also has herbalist training and educational certificates in the field of medical ethnobotany. Feel free to send him an email at! You can also connect with Dr. Brian Staiger on LinkedIn.

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