Does Benadryl (Diphenhydramine) Affect Birth Control Pills?
In our latest question and answer, our pharmacist discusses if it is safe to take Benadryl with birth control pills.
Does diphenhydramine affect birth control? Does it make them less effective?
Sep 10, 2022- Benadryl and birth control pills are safe to take together with no known interactions between them.
- Benadryl is a sedating antihistamine that typically starts working within 15 to 30 minutes and lasts about 4 to 6 hours.
- Birth control pills work mainly by preventing ovulation and do not protect against sexually transmitted infections.
Answer
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
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Glossary — Terms in This Answer
- Antihistamine
- A medication that blocks histamine, a chemical in the body that causes allergic reactions and inflammation.
- H1-blocker
- A type of antihistamine that specifically blocks histamine receptors responsible for allergic symptoms.
- Parenteral
- Administered by injection rather than by mouth or through the skin.
- Progestin
- A synthetic hormone that mimics progesterone and is used in birth control pills.
- Ovulation
- The release of an egg from the ovary that can be fertilized to cause pregnancy.
- Cervical mucus
- Fluid produced by the cervix that changes consistency during the menstrual cycle and affects sperm movement.
- Dysmenorrhea
- Severe pain or cramping that occurs during menstruation.
- Amenorrhea
- The absence or stopping of menstrual periods.
Dr. Brian Staiger, PharmD
Doctor of Pharmacy, board certified clinical pharmacist (BCPS), American Herbalist Guild, Medication Therapy Management certified
Brian Staiger, PharmD, BCPS, is a licensed pharmacist with more than 13 years of experience across retail pharmacy, clinical pharmacy, medication safety, pharmacy program development, and healthcare administration. He is the founder of HelloPharmacist.com, where he helps patients...
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