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Overview: Doxylamine is an antihistamine that is used to help people who have trouble falling asleep or to help with allergy symptoms. The most common side effect is drowsiness. It may cause excitability in children. Do not drive or do other activities that require alertness or coordination until you know how doxylamine affects you.

Uses

What is doxylamine used for?

Doxylamine is commonly used for the following conditions.

  • To help people who have trouble falling asleep (insomnia)
  • To reduce allergy symptoms, such as a runny nose, itchy or watery eyes, sneezing, or an itchy nose or throat

These uses may vary, depending on the specific doxylamine product used. Doxylamine may also be used for other conditions as determined by your health care provider.

How does doxylamine work (mechanism of action)?

Doxylamine is an antihistamine. It works by blocking the effect of a substance in your body called histamine. 

How is doxylamine supplied (dosage forms)?

Brands and other names

  • Sambrosa Night
  • Unisom
  • ZzzQuil

Example dosage forms and strengths

  • 9.78 mg/3 mL oral syrup
  • 25 mg oral tablets

How should I store doxylamine?

Doxylamine should usually be stored at room temperature, between 68 F and 77 F (20 C and 25 C). It can be exposed to temperatures between 59 F and 86 F (15 C and 30 C) for shorter periods of time, such as when you're transporting it. Store it in a cool, dry place. Some doxylamine products may need to be stored in the refrigerator, between 36 F and 46 F (2 C and 8 C). Check the label of your specific product or ask your pharmacist if you have questions about how to store doxylamine.

Side Effects

What are the most common side effects of doxylamine?

The most common side effects of doxylamine are listed below. Tell your health care provider if you have any of these side effects that bother you.

  • Drowsiness
  • Excitability (especially in children)

There may be other side effects of doxylamine that are not listed here. Contact your health care provider if you think you are having a side effect of a medicine. In the U.S., you can report side effects to the FDA at www.fda.gov/medwatch or by calling 800-FDA-1088 (800-332-1088). In Canada, you can report side effects to Health Canada at www.health.gc.ca/medeffect or by calling 866-234-2345.

What are the serious side effects of doxylamine?

While less common, the most serious side effects of doxylamine are described below, along with what to do if they happen.

Severe Allergic Reactions. Doxylamine may cause allergic reactions, which can be serious. Stop taking doxylamine and get help right away if you have any of the following symptoms of a serious allergic reaction.

  • Breathing problems or wheezing
  • Racing heart
  • Fever or general ill feeling
  • Swollen lymph nodes
  • Swelling of the face, lips, mouth, tongue, or throat
  • Trouble swallowing or throat tightness
  • Itching, skin rash, or pale red bumps on the skin called hives
  • Nausea or vomiting
  • Dizziness, feeling lightheaded, or fainting
  • Stomach cramps
  • Joint pain

Warnings & Precautions

Who should not use doxylamine?

Allergies to Ingredients. People who are allergic to any of the following should not take doxylamine.

  • Doxylamine 
  • Any of the ingredients in the specific product being used

Your pharmacist can tell you all of the ingredients in the specific doxylamine products they stock.

What should I know about doxylamine before using it?

There are several forms of doxylamine available. Read and follow the instructions for the product you have and make sure you understand how to use it properly. If you have any questions, talk to your pharmacist or other health care provider.

Keep doxylamine out of the reach of children. If your doxylamine product should be kept in a refrigerator, take special care to keep it away from children who also use the refrigerator.

If you are taking doxylamine liquid, use an accurate measuring device to measure your dose. A household spoon is not an accurate measuring device and may cause you to take the wrong dose. Ask your pharmacist what measuring device to use.

Doxylamine can affect your alertness or coordination. Do not drive or do other activities that require alertness or coordination until you know how doxylamine affects you.

If you are taking doxylamine for sleep, do not take it unless you have time for a full night's sleep. This helps to avoid daytime drowsiness or other side effects. Tell your health care provider if you have trouble sleeping for more than two weeks. Your health care provider may need to see if a medical condition is causing your sleep problems.  

What should I tell my health care provider before using doxylamine?

Tell your health care provider about all of your health conditions and any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. This will help them know if doxylamine is right for you.

In particular, make sure that you discuss any of the following.

Current and Past Health Conditions. Tell your health care provider if you have any of the following. 

Other Medicines and Supplements. Doxylamine may interact with other medicines and supplements. Before you take doxylamine, tell your health care provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. See the Interactions section for more details.

Pregnancy. It is not known if or how doxylamine could affect pregnancy or harm an unborn baby. Tell your health care provider if you are pregnant or plan to become pregnant. Your health care provider will let you know if you should take doxylamine while you are pregnant or trying to get pregnant.

Breastfeeding. It is not known if doxylamine passes into breast milk. Tell your health care provider if you are breastfeeding or plan to breastfeed. Your health care provider will let you know if you should take doxylamine while breastfeeding.

Interactions

Does doxylamine interact with foods or drinks?

There are no known interactions between doxylamine and foods or non-alcoholic drinks.

Do not drink alcohol while you are taking doxylamine. The risk of drowsiness may be increased if you drink alcohol while taking doxylamine.

Does doxylamine interact with other medicines (drug interactions)?

Always tell your health care provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using.

In particular, make sure that you discuss if you are using any of the following before taking doxylamine.

  • Any other antihistamine, such as chlorpheniramine or diphenhydramine (Benadryl), which is a medicine commonly used to treat allergy symptoms
  • Any other medicine that causes dizziness and sleepiness, such as prescription pain medicines, sleep medicines, or medicines for anxiety

This may not be a complete list of medicines that can interact with doxylamine. Always check with your health care provider.

Does interact with other drugs you are taking?

Enter your medication into the WebMD interaction checker

Overdose/Missed Dose

What should I do if I accidentally use too much doxylamine?

If you or someone else has taken too much doxylamine, get medical help right away, call 911, or contact a Poison Control center at 800-222-1222.

What should I do if I miss a dose of doxylamine?

If you miss a dose, take it as soon as you remember. If it is almost time for your next dose, skip the missed dose and only take the next dose. Do not take double or extra doses.