Most adults can take 25–50 mg of Benadryl (diphenhydramine) every 4–6 hours as needed, but should not exceed 300 mg in 24 hours. Always follow the package label and ask a doctor or pharmacist if you are unsure, have medical conditions, or take other medications.

Typical adult dosage

  • Standard tablet/capsule is 25 mg of diphenhydramine.
  • Usual adult dose: 25–50 mg by mouth every 4–6 hours as needed for allergies, cold symptoms, or itching.
  • Maximum: 6 doses in 24 hours (total 300 mg).

Children’s dosing (important)

  • Children 12 years and older: same as adults, 25–50 mg every 4–6 hours, max 300 mg per day.
  • Children 6–11 years: 12.5–25 mg every 4–6 hours, max 150 mg per day; use child formulations and a proper measuring device.
  • Children under 6: only if a pediatrician specifically tells you dose and schedule; under 2 years, do not use over-the-counter Benadryl for allergies unless directly instructed by a doctor.

Safety and when not to use

  • Older adults (about 65+), people with heart disease, glaucoma, urinary retention, breathing problems, or who are pregnant/breastfeeding should talk to a clinician before taking Benadryl.
  • Benadryl causes drowsiness and slows reaction time; do not drive, drink alcohol, or combine with other sedating drugs or sleep meds.
  • Never use it just to “help a child sleep”; this is unsafe and not an approved use.

Overdose and danger signs

  • Taking much more than the maximum daily dose can cause serious symptoms: confusion, agitation, hallucinations, fast heart rate, seizures, or trouble breathing.
  • Extremely high doses—sometimes taken in online “challenges”—have led to life-threatening heart rhythm problems and even death.
  • If someone may have taken too much, or has any of the above symptoms, call emergency services or poison control immediately.

Quick Scoop (HTML table)

html

<table>
  <thead>
    <tr>
      <th>Group</th>
      <th>Typical single dose</th>
      <th>How often</th>
      <th>Max per 24 hours</th>
    </tr>
  </thead>
  <tbody>
    <tr>
      <td>Adults &amp; ≥12 years</td>
      <td>25–50 mg</td>
      <td>Every 4–6 hours as needed</td>
      <td>300 mg (6 doses)</td>
    </tr>
    <tr>
      <td>Children 6–11 years</td>
      <td>12.5–25 mg</td>
      <td>Every 4–6 hours as needed</td>
      <td>150 mg (6 doses)</td>
    </tr>
    <tr>
      <td>Children &lt;6 years</td>
      <td>Only if doctor gives exact dose</td>
      <td>Use medical advice only</td>
      <td>Follow doctor’s instructions</td>
    </tr>
  </tbody>
</table>

If you are ever unsure about “how many mg of Benadryl can I take,” treat the package directions as the absolute ceiling and ask a doctor, urgent care, or pharmacist before taking more.

TL;DR: For most healthy adults, 25–50 mg every 4–6 hours, max 300 mg per day; lower doses for kids, and always get medical advice for young children, older adults, pregnancy, or other health conditions.

Information gathered from public forums or data available on the internet and portrayed here.