Doxycycline is a generic drug prescribed for various bacterial infections, skin conditions, and malaria prevention. As with other drugs, doxycycline can cause side effects, such as decreased appetite, diarrhea, and skin rash.

Doxycycline is available in many brand-name versions: Doryx, Doryx MPC, Acticlate, Oracea, and Vibramycin.

This article focuses on doxycycline oral tablets and oral capsules, specifically:

  • immediate-release tablets
  • immediate-release capsules
  • delayed-release tablets
  • combined immediate-release and delayed-release capsules

Immediate release means the drug is released soon after you swallow the tablet. Delayed release means the drug is released into your body a certain amount of time after you swallow it.

Doxycycline also comes as an oral suspension and an injection, but this article does not cover these forms.

Read on to learn about potential common, mild, and serious side effects of doxycycline oral tablets and oral capsules. For a general overview of the drug, including details about its uses, refer to this article.

Doxycycline comes in two different versions: doxycycline hyclate and doxycycline monohydrate. Hyclate and monohydrate are the salt forms of the drugs. The purpose of a salt form is to help your body dissolve and absorb the drug better.

Both doxycycline hyclate and doxycycline monohydrate contain the same active drug: doxycycline. The two forms of doxycycline can be used to treat similar conditions and may cause similar side effects. The two drugs differ only in the type of salt they contain. Both forms are currently considered equally effective.

Side effects of 100-mg strength

Doxycycline comes in many different strengths, depending on which form of the drug you take. In most cases, side effects of the 100-milligram (mg) strengths of doxycycline hyclate and doxycycline monohydrate are the same. There aren’t side effects specific to the 100-mg strength of either drug.

Keep in mind that you may have an increased risk of side effects if you take a higher strength of doxycycline. For example, if you’re prescribed the 40-mg strength, you may have fewer and less severe side effects than someone taking the 100-mg strength.

If you have questions about doxycycline’s forms, strengths, or side effects, ask your doctor or pharmacist.

Doxycycline can cause certain side effects (also known as adverse effects), some of which are more common than others. These side effects may be temporary, lasting a few days to weeks. However, if the side effects last longer than that, bother you, or become severe, be sure to talk with your doctor or pharmacist.

These are just a few of the more common side effects that people taking doxycycline in clinical trials reported:

For details about all side effects reported in clinical trials, you can refer to the prescribing information for the form of doxycycline you’re taking. You can find these in the “Sources” listed at the end of this article.

* For more information about this side effect, see “Side effect specifics” below.

Mild side effects that people taking doxycycline have reported include:

This list doesn’t include all possible mild side effects of the drug. For details about all side effects reported in clinical trials, you can refer to the prescribing information for the form of doxycycline you’re taking. You can find these in the “Sources” listed at the end of this article.

These side effects may be temporary, lasting a few days to weeks. However, if the side effects last longer than that, bother you, or become severe, be sure to talk with your doctor or pharmacist.

Note: After the Food and Drug Administration (FDA) approves a drug, it tracks side effects of the medication. If you develop a side effect while taking doxycycline and want to tell the FDA about it, visit MedWatch.

* For more information about this side effect, see “Side effect specifics” below.

Doxycycline may cause serious side effects. Usually, serious side effects are rare.

If you develop serious side effects while taking doxycycline, call your doctor right away. If the side effects seem life threatening or you think you’re having a medical emergency, immediately call 911 or your local emergency number.

Serious side effects and their symptoms that have been reported include:

  • Serious skin rash. Symptoms can include:
    • peeling of the skin
    • blistering
    • fever
  • Hemolytic anemia (a condition which destroys red blood cells within blood vessels). Symptoms can include:
  • Decreased levels of white blood cells or platelets. Symptoms can include:
    • fever
    • fatigue
    • bruising or bleeding more easily
  • Intracranial hypertension (high blood pressure in the head). Symptoms can include:
    • fever
    • headache
    • eye-related side effects, such as double vision or vision loss
  • Pancreatitis (inflammation of the pancreas). Symptoms can include:
    • abdominal pain
    • fever
    • nausea or vomiting
  • Diarrhea due to a bacterium called Clostridium difficile. Symptoms can include:
    • watery diarrhea
    • abdominal cramping
    • fever
  • Ulcers and inflammation in your esophagus. Symptoms can include:
    • difficulty swallowing
    • nausea and vomiting
    • cough
    • indigestion
  • Pericarditis.*
  • Severe allergic reaction.*

The list above may not include all possible serious side effects of the drug. For details about all side effects reported in clinical trials, you can refer to the prescribing information for the form of doxycycline you’re taking. You can find these in the “Sources” listed at the end of this article.

* For more information about this side effect, see “Side effect specifics” below.

If doxycycline is taken at certain times during pregnancy, the drug may cause tooth discoloration in the child. The discoloration can also occur in children younger than age 8 years who are given the drug. This side effect may be permanent, causing teeth to become yellow, gray, or brown.

Tooth discoloration is more common when you take doxycycline for a long time. However, it can occur with a short treatment of doxycycline in children. In addition, decreased tooth enamel has been reported when the drug was given to children younger than age 8 years.

Due to these risks, doctors do not typically recommend doxycycline for use in children younger than age 8 years. However, doctors may prescribe the drug for some children in this age group. For example, doxycycline is the recommended treatment for anthrax in children.

If you have questions or concerns about side effects that doxycycline can cause in children, talk with your child’s doctor.

Learn more about some of the side effects that doxycycline may cause.

Nausea and vomiting

Nausea and vomiting are common side effects of doxycycline.

What you can do

If you experience nausea and vomiting from taking doxycycline, talk with your doctor. They may recommend taking the drug with milk or food. This can lower your risk of nausea and vomiting with the drug.

Photosensitivity

It’s possible for doxycycline to cause photosensitivity, which may also be called sun sensitivity. This means that you can get sunburned more easily than usual, and it may be more serious.

Photosensitivity is a common side effect of doxycycline. Symptoms of photosensitivity reactions can include:

  • skin rash or blotchiness
  • blistering
  • itchiness or burning of the skin

What you can do

If you develop a photosensitivity reaction, talk with your doctor. They can recommend treatment options, such as a cool compress.

In addition, you should try to limit exposure to sunlight and UV light while taking doxycycline. If you need to be outdoors, wear loose-fitting clothes that will protect your skin from the sun. Your doctor will likely recommend wearing protective clothing and sunscreen to help prevent a photosensitivity reaction.

Pericarditis

Although very rare, it’s possible for doxycycline to cause a heart-related side effect called pericarditis. This is swelling around your heart caused by an allergic reaction. This can cause symptoms such as:

What you can do

If you develop any of these symptoms during doxycycline treatment, talk with your doctor. They might order tests for your heart to determine whether you have pericarditis.

If you develop pericarditis, your doctor can treat it. They’ll also likely recommend that you stop taking doxycycline. In this case, they may suggest a different medication for your infection.

Allergic reaction

As with most drugs, doxycycline can cause an allergic reaction in some people.

Mild allergic reaction

Symptoms can be mild and may include:

  • skin rash
  • itching
  • flushing

What you can do about a mild allergic reaction

For mild symptoms of an allergic reaction, call your doctor right away. They may recommend ways to ease your symptoms and determine whether you should keep taking doxycycline.

Serious allergic reaction

Allergic reactions with doxycycline can also be serious. Symptoms of a serious allergic can include:

  • swelling under your skin, typically in your eyelids, lips, hands, or feet
  • swelling of your mouth, tongue, or throat, which can make it hard to breathe

It’s important to note that certain serious allergic skin reactions have occurred in people taking doxycycline. Examples of these reactions include Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN). Symptoms of SJS and TEN can include:

  • blistering, peeling skin
  • a rash of small purple or dusky-red skin spots
  • body aches

What you can do about a serious allergic reaction

If you develop symptoms of a serious reaction described above, immediately call 911 or your local emergency number, or go to the closest emergency room. These reactions can be life threatening, and they require immediate medical care.

Most side effects that people experience with doxycycline are short term. This means that the side effects will likely go away after stopping treatment.

However, in rare cases, it’s possible to develop long-term side effects with doxycycline. Examples of these include:

It’s important to note that if you take doxycycline long term, your side effects may last throughout your treatment. For example, if you use doxycycline for acne, you will typically take it long term, which means the side effects may be longer lasting.

If you have concerns about long-term side effects of doxycycline, talk with your doctor or pharmacist.

Doxycycline may cause several side effects. Here are some frequently asked questions about the drug’s side effects and their answers.

Should I expect side effects such as abdominal pain or an upset stomach with doxycycline?

People taking the drug in clinical trials did not specifically report abdominal pain and upset stomach. However, they did report nausea and vomiting in clinical trials. This might be similar to an upset stomach and could cause abdominal pain.

Abdominal pain and upset stomach can be symptoms of other side effects of doxycycline. For example, the drug may cause severe diarrhea or pancreatitis (inflammation of the pancreas). Either of these conditions may cause abdominal pain or upset stomach.

It’s important to note that you should drink plenty of liquid when you take your dose of doxycycline. This helps make sure the drug doesn’t irritate your throat.

If you experience pain in your abdomen or an upset stomach during your treatment with doxycycline, talk with your doctor. They can help determine the cause and how to treat your symptoms.

Does doxycycline cause headaches?

No, people taking doxycycline in clinical trials did not report headaches.

It is possible for a headache to be a symptom of another doxycycline side effect. In rare cases, this drug can cause severe diarrhea (which may lead to dehydration) and increased pressure in your head. Dehydration and the increased pressure may cause a headache.

If you experience headaches during doxycycline treatment, especially ones that bother you or are severe, talk with your doctor. They can help determine the cause and recommend a treatment option.

Is constipation a possible side effect of doxycycline?

No, constipation wasn’t a side effect reported by people taking doxycycline in clinical trials. Instead, people taking this drug reported diarrhea as a common side effect.

Your doctor can help with other concerns you may have about constipation.

Can doxycycline cause weight gain?

No, weight gain wasn’t a side effect that people taking this medication reported in clinical trials.

You can speak with your doctor if you have concerns about weight gain.

Does hair loss occur with doxycycline use?

Hair loss wasn’t a side effect reported by people taking doxycycline in clinical trials.

Another medication prescribed for acne, called isotretinoin (Zenatane), may cause hair loss as a side effect.

If you have hair loss that’s concerning, talk with your doctor.

You shouldn’t experience side effects after stopping treatment with doxycycline. People who stopped taking the drug in clinical trials did not report side effects after stopping treatment.

However, if you’re taking doxycycline to treat acne or rosacea, the symptoms of your condition can return when you stop treatment. This is because the drug was working to treat these conditions, and you’re no longer taking it. For example, if you stop taking doxycycline for acne, your acne may flare up again.

You should not stop treatment with doxycycline without first consulting your doctor. They can help determine whether it’s safe to stop taking the drug or whether a different medication is a better option.

Be sure to talk with your doctor about your health history before you take doxycycline. This drug may not be the right treatment option for you if you have certain medical conditions or other factors that affect your health. These are considered to be drug-condition or drug-factor interactions. The conditions and factors to consider include:

Diarrhea: It’s possible for doxycycline to cause diarrhea, which can be severe. Severe diarrhea can be dangerous and lead to dehydration. If you already have diarrhea, taking doxycycline may worsen it. You can talk with your doctor to determine whether it’s safe for you to take doxycycline.

Fungal infections: Tell your doctor if you have any fungal infections, such as a yeast infection. It’s possible for antibiotics such as doxycycline to increase your risk of fungal infections. If you already have a fungal infection, taking this medication may worsen your infection. In this case, your doctor may treat your infection before prescribing doxycycline.

Allergic reaction: If you’ve had an allergic reaction to doxycycline or any of its ingredients, your doctor will likely not prescribe doxycycline. They also won’t prescribe doxycycline if you’ve had an allergic reaction to similar antibiotics, including tetracycline, minocycline, or tigecycline. Taking doxycycline could cause you to have another allergic reaction. Ask your doctor what other medications may be better options for you.

Alcohol with doxycycline

There are no known interactions between doxycycline and alcohol.

However, drinking large amounts of alcohol may reduce your immune system activity, sometimes referred to as weakening your immune system.

Doxycycline treats certain infections that occur when bacteria enter your body. Your immune system works to fend off the bacteria. Alcohol can reduce your immune system activity. So if you’re taking doxycycline, drinking alcohol may make it harder for your body to fight the infection.

In addition, consuming alcohol while taking doxycycline may increase your risk of side effects from the drug. For example, doxycycline may cause nausea or vomiting. Alcohol can also cause these effects. So the combination may further increase your risk of side effects.

If you’d like to drink alcohol while you’re taking doxycycline, talk with your doctor. They can advise you on how much alcohol, if any, may be safe for you.

Pregnancy and breastfeeding while taking doxycycline

Doxycycline treatment is not typically recommended during the second or third trimester of pregnancy or while breastfeeding. (The second trimester refers to weeks 13 to 28. The third trimester refers to weeks 29 to 40.)

If you take doxycycline during the second or third trimester, the drug may increase the risk of bone or tooth development problems in the child.

Clinical trials did not show an increased risk of congenital anomalies when people took doxycycline during the first trimester of pregnancy. (Congenital anomalies are also known as birth defects. And the first trimester refers to weeks 1 to 12.)

It’s also important to note that doxycycline passes into breast milk. At this time, it’s unknown exactly what effects the drug may have on a child who is breastfed. However, because doxycycline may cause bone or tooth problems, it’s recommended to avoid taking the drug while breastfeeding.

If you’re pregnant or planning to become pregnant, talk with your doctor. You should also talk with them if you’re breastfeeding or considering it. Your doctor can help determine whether another medication may be a safer treatment option for you.

Usually, side effects from doxycycline are mild. If you’d like to learn more about doxycycline, talk with your doctor or pharmacist. They can help answer any questions you have about side effects from taking the drug. Referring to the following articles can provide you with more information:

Disclaimer: Medical News Today has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or another healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.