As is the case with any other medication, there may be some instances where doxycycline use is not recommended or usage will have to be adjusted in order to prevent or reduce the risk of negative interactions occurring from other drugs, medical conditions, or even food and drink.
Drug Interactions
According to the U.S. National Library of Medicine, drugs that may interact with doxycycline include the following.
- Anticoagulant (blood-thinning) therapy (Ex. warfarin)
- Penicillin
- Antacids containing aluminum, calcium, or magnesium, and iron-containing preparations
- Bismuth subsalicylate (Bismuth)
- Barbiturates, carbamazepine (Tegretol XR, Equetro, Tegretol), and phenytoin (Phenytek, Dilantin Kapseal, Dilantin Infatabs)
- Hormonal contraceptive pills
- Methoxyflurane (Penthrox)
- Sucralfate
- Rifampin
Please note that this list may not be complete, and other interactions with drugs not listed here may occur.
Doxycycline and Anticoagulant Therapy
Patients who are on anticoagulant therapy may require dosage adjustments because tetracyclines have been shown to depress plasma prothrombin activity. In other words, doxycycline may increase the effect of warfarin or coumadin, and therefore you may require a smaller dose of warfarin while taking doxycycline.
Doxycycline and Penicillin
It is best to avoid taking tetracyclines in conjunction with penicillin because it may interfere with the bactericidal (bacteria-killing) action of penicillin.
Doxycycline and Antacids
Antacids containing aluminum, calcium, or magnesium, and iron-containing preparations may inhibit the absorption of doxycycline. It is advisable to separate out taking these by 1-2 hours from taking doxycycline.
Doxycycline and Bismuth Subsalicylate
Bismuth subsalicylate impairs absorption of doxycycline. It is advisable to separate out taking these by 1-2 hours from taking doxycycline
Doxycycline and Barbiturates, Carbamazepine, and Phenytoin
Barbiturates, carbamazepine, and phenytoin decrease the half-life of doxycycline.
Doxycycline and Contraceptive Pills
Use of tetracycline may reduce oral contraceptives effectiveness. (You can visit our page on non-hormonal contraceptive options to learn more about taking extra precautions.)
Doxycycline and Methoxyflurane
The concurrent use of tetracycline and methoxyflurane has been reported to cause fatal renal (kidney) toxicity.
Food Interactions
Sometimes the foods we eat and the beverages we drink can also interact with our medications.
Food and drink that may interact with doxycycline include:
- Dairy
- Alcohol
- Coffee
Please note that this list may not be complete, and there may be other foods and beverages that interact with this drug.
Doxycycline and Dairy
Dairy foods like milk, cheese, and yogurt can inhibit doxycycline absorption. It is therefore recommended not to consume dairy food together with your antibiotic dose. You can have dairy products a few hours before or after your dose.
Doxycycline and Alcohol
For more information, please visit our page on doxycycline and alcohol interactions.
Doxycycline and Coffee
Tetracycline antibiotics are highly acidic. Therefore ,it is best to avoid consuming acidic beverages, such as orange juice, apple juice, and coffee when taking doxycycline.
Disease & Conditions Interactions
Sometimes certain medications can increase the risk of negative side effects for patients with certain diseases or other medical conditions.
According to the U.S. National Library of Medicine, diseases and medical conditions that are known to negatively interact with doxycycline include:
- Drug/laboratory test interactions
- Carcinogenesis, mutagenesis, impairment of fertility
- Pregnancy
Please note that this list may not be complete, and there may be other diseases and medical conditions where patients should not take doxycycline.
Doxycycline and Laboratory Test interactions
Doxycycline can elevate urinary catecholamine levels, which can interfere with fluorescence tests.
Doxycycline and Cancerogenesis, Impairment of Fertility
There is evidence of oncogenic (cancerous) activity in rats in studies with the related antibacterial drugs oxytetracycline (adrenal and pituitary tumors) and minocycline (thyroid tumors). However, extensive studies have not been conducted.
Doxycycline administered orally at dosage levels as high as 250 mg/kg/day had no apparent effect on the fertility of female rats. Effect on male fertility has not been studied.
Doxycycline and Pregnancy
For more information, please visit our page on doxycycline and pregnancy risks.
Other Interactions
Doxycycline and Sun Exposure
Doxycycline may make your skin more sensitive to sunlight. Therefore, exposure to sunlight, even for short periods of time, may cause adverse reactions. These reactions include:
- skin rash,
- itching,
- redness or other discoloration of the skin, or
- a severe sunburn.
As such, it is recommended to avoid excessive sun exposure or artificial ultraviolet light when taking doxycycline. Always wear sun protective clothing and an SPF50+ sunscreen when exposure to sunlight is unavoidable.
Disclaimer: this article does not constitute or replace medical advice. If you have an emergency or a serious medical question, please contact a medical professional or call 911 immediately. To see our full medical disclaimer, visit our Terms of Use page.
