Reviewed by Dr Samantha Miller MB ChB
(2017, University of Glasgow)
GMC number: 7561464
Information last reviewed 26/01/2021
Doxycycline is an antibiotic used to treat a broad range of bacterial infections, including chlamydia. It can also be used to protect against malaria when travelling.
Doxycycline works by stopping the growth and replication of bacteria. This helps to prevent the spread of infection and allows the body’s immune system to kill off the remaining bacteria.
The standard seven-day course of doxycycline cures 98% of chlamydia infections. Always complete the course of antibiotics as prescribed. If your symptoms persist after you have completed treatment, you may need additional tests or treatment from your doctor.
Dose |
Usually 1 or 2 tablets once per day, depending on treatment |
Type of medicine |
Tetracycline antibiotic |
Mechanism |
Inhibits protein synthesis; prevent bacteria from reproducing. |
Available Size |
14 |
Available Strengths |
100mg |
Active Ingredient |
Doxycycline hyclate |
Price |
From 63p per tablet |
Side Effects |
Can include sensitivity to sunlight, nausea, vomiting, rash, hives, diarrhoea and loss of appetite |
The active ingredient in doxycycline tablets is doxycycline hyclate.
Different brands of doxycycline contain different inactive ingredients. The inactive ingredients in doxycycline tablets may include sucrose, maize starch, crospovidone, basic butylated methacrylate copolymer (Eudragit E100) and purified talc.
You should take doxycycline as prescribed by your doctor. The usual dose for chlamydia treatment is one 100mg tablet taken twice a day for seven days.
For the treatment of chlamydia, the usual dose is one 100mg tablet of doxycycline taken twice a day. Each tablet should be swallowed whole with a glass of water, at around the same time every day.
Doxycycline can cause irritation to the oesophagus (food pipe). For this reason, you should avoid lying down for 30 minutes after taking it. If you find that the medication causes nausea, vomiting or heartburn, take the tablets with food.
Doxycycline starts to work straight away, but it may take a few days before symptoms improve.
Your symptoms may improve before you complete the course of antibiotics. However, it is important that you always complete the course, even if your symptoms have resolved. Not completing a course of antibiotics can lead to antibiotic resistance. Antibiotic resistance can make antibiotics less effective and bacterial infections much harder to treat.
Doxycycline can be taken with or without food, and should always be taken with a full glass of water. If you find taking the tablets makes you feel nauseous, it is recommended to take Doxycycline with a meal.
Your doxycycline tablets should be taken at the same time each day. Usually, if you miss a tablet you should take it as soon as you remember. However, if it is only a few hours until your next dose, skip the missed dose. Do not take a ‘double dose’ to make up for a missed dose.
You should always finish a course of antibiotics, even if your symptoms clear up before you have completed the course. Failure to finish the course may result in the infection persisting or antibiotic resistance. Antibiotic resistance is where bacteria adapt to protect themselves from certain antibiotics, this resistance makes it harder to treat the infection.
Like all medications, doxycycline can cause side effects. Common side effects of doxycycline include nausea/vomiting, loss of appetite, light-headedness, headaches, light sensitivity (photosensitivity), rash, shortness of breath and an increased heart rate.
It is also possible to experience a number of other side effects. Please read the patient information leaflet for a full list of possible side effects.
In rare cases, people also experience severe side effects which require immediate medical attention. Severe side effects include:
If any of these apply, stop taking doxycycline and seek emergency medical attention.
Over the counter painkillers like paracetamol and ibuprofen may help to relieve headaches.
If you experience nausea or vomiting you can try to take your dose of doxycycline with a meal. If you are vomiting, it is important to stay well hydrated. Speak to your doctor if you are vomiting shortly after taking doxycycline.
When taking doxycycline, you can become more sensitive to sunlight (photosensitivity). Therefore, it is recommended that you avoid strong sunlight, keep your skin covered and apply sunscreen. If it will not be possible for you to avoid excessive sun exposure, you should speak to your doctor about alternative treatments.
Doxycycline can interact with other medications, potentially making them less effective. For this reason, it is important to inform the prescribing doctor of any other medications or treatments you are taking. This includes herbal remedies, recreational drugs and any over the counter treatments you are using.
The patient information leaflet contains a full list of medications that are known to interact with doxycycline. This includes some antacids, antibiotics, anticoagulants (warfarin), and anti-epileptic drugs amongst others.
You should not use doxycycline if you are allergic to doxycycline or any other tetracycline antibiotic. You should not use this medication if you are pregnant, planning to become pregnant, or breastfeeding.
Inform the prescribing doctor if you are taking any other medication, or if you have any other health conditions. Doxycycline may not be suitable for you if you have kidney or liver problems, myasthenia gravis, systemic lupus erythematosus (SLE) or porphyria. For a full list of conditions, please see the patient information leaflet.
Doxycycline and alcohol should not be taken together. Alcohol can reduce the effectiveness of doxycycline.
Doxycycline should not be taken during pregnancy as it can affect the development of bones and teeth in the baby. Do not take doxycycline if you are pregnant, breastfeeding or planning to become pregnant whilst taking doxycycline. Your doctor can recommend a suitable alternative.
Doxycycline can increase your sensitivity to UV light. UV light is found in sunlight, sunlamps and sunbeds. When taking doxycycline, you may be more likely to experience sunburn or skin damage in response to UV light. You should inform the prescribing doctor if you anticipate being exposed to strong sunlight or UV light.
Our bodies naturally have a number of different bacteria and organisms that live on their surfaces. Doxycycline can kill off some of the bacteria that help to keep the other organisms in check. When there is an overgrowth of candida yeast, this can cause a thrush infection. If you experience thrush, speak to your doctor or pharmacist about treatment options.
Doxycycline can lead to yellow-brown discolouration of the teeth. For this reason, it is usually avoided in children under 8 years old. It may be possible to remove discolouration with dental treatments, although this may not be successful in all cases.
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