Most serious warnings may include:

• severe allergic reactions including rash, swelling, or difficulty breathing

• severe diarrhea caused by intestinal infection

• liver problems

• severe skin reactions

• inflammation or ulceration of the esophagus

• increased sensitivity to sunlight

Doxycycline can cause photosensitivity, which means your skin may become more sensitive to sunlight and may burn more easily than normal. 

Like other antibiotics, doxycycline may occasionally allow overgrowth of non-susceptible organisms such as fungi. If symptoms worsen or new symptoms appear during treatment, contact your provider.

Stop taking this medication and seek immediate medical care if you experience:

• signs of a severe allergic reaction such as rash, hives, itching, or swelling of the face, lips, tongue, or throat 

• difficulty breathing or trouble swallowing

• severe or unusual drowsiness, confusion, or inability to stay awake

• sudden vision changes, including blurred vision that does not resolve 

• severe dizziness or symptoms that worsen instead of improving

• any new or concerning symptoms that feel severe or unexpected

Tell Your Healthcare Provider

Contact your healthcare provider if you experience:

• persistent or worsening dizziness or vertigo

• ongoing drowsiness that interferes with daily activities

• dry mouth, fatigue, or headache that becomes bothersome or does not improve 

• vomiting or symptoms that do not improve with treatment 

• side effects that feel unusual, severe, or concerning

• any questions about how to safely continue or adjust your medication

Do not take doxycycline if you:

• have a known allergy to doxycycline or other tetracycline antibiotics (such as tetracycline or minocycline), as this may cause a serious allergic reaction 

• are pregnant or may become pregnant, as doxycycline can harm an unborn baby and may affect bone and tooth development 

• are breastfeeding, unless specifically directed by your healthcare provider, as this medication can pass into breast milk and affect a nursing infant 

• are a child under 8 years old, unless your provider determines it is necessary, as doxycycline can cause permanent tooth discoloration and affect bone growth 

• have previously experienced severe reactions to tetracycline antibiotics, including serious skin reactions or hypersensitivity

If you are unsure whether this medication is safe for you, speak with your healthcare provider before starting treatment.

Tell your provider if you:

• are allergic to doxycycline, tetracyclines, or other medications

• have liver disease

• have difficulty swallowing pills or a history of esophageal irritation

• are pregnant or planning to become pregnant

• are breastfeeding

• take blood thinners or other prescription medications

• take supplements containing calcium, magnesium, iron, or zinc

Doxycycline is generally not recommended during pregnancy because tetracycline antibiotics may affect fetal bone and tooth development.

This medication is typically not recommended for children under the age of 8 unless specifically prescribed by a provider.

Doxycycline is generally well tolerated, but like all medications, it can cause side effects.

Common side effects may include:

• nausea or upset stomach

• vomiting

• diarrhea

• loss of appetite

• sensitivity to sunlight (sunburn more easily) 

These side effects are usually mild and may improve as your body adjusts to the medication. Taking doxycycline with a full glass of water and following your provider’s instructions may help reduce stomach discomfort.

Serious side effects (seek medical care immediately) may include:

• severe allergic reactions such as rash, hives, swelling of the face or throat, or difficulty breathing 

• severe skin reactions, including blistering, peeling skin, or painful rash

• severe or persistent headache, vision changes, or pressure behind the eyes, which may be a sign of increased pressure in the brain (intracranial hypertension) 

• severe diarrhea, watery stools, or bloody stools, which may indicate a serious intestinal condition (C. difficile-associated diarrhea) 

• difficulty swallowing or chest pain when swallowing, which may indicate irritation or ulceration of the esophagus

• unusual bruising or bleeding, or signs of liver problems such as yellowing of the skin or eyes, dark urine, or severe fatigue 

Contact your healthcare provider if you experience side effects that are persistent, worsening, or concerning.

Taking more doxycycline than prescribed may increase the risk of side effects and toxicity.

Symptoms of overdose may include:

• severe nausea or vomiting

• persistent stomach pain

• diarrhea

• loss of appetite

• irritation or ulceration of the throat or esophagus

In some cases, taking too much doxycycline may also increase the risk of liver-related side effects or other serious reactions. 

If you think you have taken too much of this medication, contact your healthcare provider, local poison control center, or seek medical care right away.

For immediate help, you can call Poison Control at 1-800-222-1222.

It is important to safely dispose of doxycycline when it is no longer needed or has expired.

• Do not keep leftover antibiotic medication for future use unless instructed by your healthcare provider

• Do not share this medication with others, even if they have similar symptoms

• Do not flush doxycycline down the toilet or pour it down the drain unless specifically instructed

Use a local medication take-back program or pharmacy disposal service when available

If a take-back option is not available:

• Mix the medication with an undesirable substance such as coffee grounds or cat litter

• Place the mixture in a sealed bag or container

• Dispose of it in your household trash

Proper disposal helps prevent accidental ingestion, misuse, and environmental contamination.