Does Benadryl (Diphenhydramine) Affect Birth Control Pills?

Benadryl and birth control pills are safe to take together.

Sep 12, 2018

Jeka asked

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

At a glance

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


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 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 is causes dry mouth, dry eyes and constipation.

The onset of action of Benadryl is around 15-30 minutes after taking 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 contain both a progestin and an estrogen)

Birth control pills are most often used to prevent pregnancy but are 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 of birth control pills include:

  • Nausea
  • Cramping
  • Bloating
  • Vomiting
  • Weight gain
  • Breast tenderness
  • Headache
  • Spotting and/or breakthrough bleeding
  1. Diphenhydramine Prescribing Information. AccessFDA
  2. Contraception. CDC

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