What side effects should I be expecting from taking doxycycline?

Signs of doxycycline allergy: difficulty breathing, hives (rash on your body), swelling of the face, lips, tongue, or throat—If you experience any of these symptoms, please call 911 or seek emergency medical care at the nearest emergency room (ER). 

Get emergency medical help:

• Suppose you have a severe skin reaction with symptoms such as skin pain, blistering/peeling red or purple skin rash that spreads, fever, sore throat, burning in the eyes. In that case, these can be signs and symptoms of Steven-Johnson syndrome. 
• Suppose you have a serious drug reaction that affects many parts of your body, with symptoms such as fever, flu-like symptoms, muscle aches, skin rash, swollen glands, unusual bruising, and yellowing of your skin or eye. In that case, this can be a presentation of drug reactions with eosinophilia and systematic symptoms (DRESS).

Call your doctor immediately if you experience any of the following signs:

• Signs of systemic infection - Fever, chill, body aches, swollen glands, pale skin, generalized weakness, and easy bleeding or bruising
• Signs of increased brain pressure - Severe headaches, ringing in your ears, dizziness, nausea, vision problems, pain behind your eyes
• Signs of liver injury - Right upper stomach pain, nausea, vomiting, loss of appetite, dark urine, jaundice (yellowing of the skin and eyes)
• Chest pain, irregular heart rhythm, shortness of breath
• Severe stomach pain
• Watery or bloody diarrhea
• Throat irritation, trouble swallowing 
• Decreased urine output to little or none

Common side effects of doxycycline:

• Upset stomach, loss of appetite
• Nausea, vomiting
• Skin rash or itching
• Darkened skin color 
• Vaginal itching or discharge

DoxycyclineOverdose: Go to the nearest emergency room or call the Poison Help line at 1-800-222-1222. You can find more information at www.poisonhelp.org/help. In case of overdosage, discontinue medication and provide supportive, symptomatic treatment. Dialysis is not beneficial in treating cases of overdosage. 

The above list on this site may not include all the possible side effects of doxycycline. Speak to your doctor or pharmacist at your local pharmacy if you have persistent side effects or any side effects that are not listed above. You can also report side effects to the Food and Drug Administration (FDA) at 1-800-FDA-1088.

Source: FDA