What Is the Difference between Minocycline and Doxycycline?

Susan Abe

Minocycline and doxycycline are both broad spectrum, long-acting, semi-synthetic antibiotics in the tetracycline family. Both are bacteriostatic, in that they prevent bacteria from reproducing by interfering with protein synthesis. They are used to treat similar conditions, including bacterial and protozoal infections. There are many differences, however, between these two drugs. They have some different specialties, spectrums of action, side effects and safety issues.

Minocycline tends to cause tiredness and dizziness.
Minocycline tends to cause tiredness and dizziness.

Doxycycline is also used as an antihelmintic or anti-worm medication in addition to its uses for bacterial and protozoal infections. It is a more bioactive medication than the other tetracycline antibiotics, including minocycline. Conversely, minocycline is a broader spectrum drug than doxycycline and is used against a wider variety of bacteria. Minocycline is also used to treat rheumatoid arthritis and is recommended in this role by the American College of Rheumatology.

Doxycycline is an antibiotic that can be used to treat urinary tract infections.
Doxycycline is an antibiotic that can be used to treat urinary tract infections.

Other differences between minocycline and doxycycline include their solubility and other chemical characteristics. Minocycline is more soluble in fats while doxycycline more easily dissolves in water. For this reason, minocycline crosses the blood-brain barrier more easily than doxycycline and causes more central nervous system (CNS) side effects. Doxycycline, as it is more soluble in water, is the better choice for urinary tract infections as its active metabolites are dissolved in and excreted via urine. This drug should not be taken with calcium supplements or calcium-rich foods that block absorption, while there is no such restriction with minocycline.

Both minocycline and doxycycline can increase one's risk of sunburn with minimal sun exposure.
Both minocycline and doxycycline can increase one's risk of sunburn with minimal sun exposure.

Some side effects differ between these medications as well. Minocycline's greater solubility in lipids causes more common central nervous system side effects, such as dizziness and lethargy. A known but rare side effect of this drug is secondary intracranial hypertension, a serious condition first indicated by headaches, disorientation and dizziness. It has also been linked to the development or exacerbation of systemic lupus and thyroid cancer. The relationship between these two conditions and minocycline has not been established as causative, but experts caution careful evaluation while on this medication.

Both minocycline and doxycycline may cause increased sensitivity to light.
Both minocycline and doxycycline may cause increased sensitivity to light.

As with all tetracycline antibiotics, minocycline and doxycycline can both cause increased photosensitivity — or sunburn — with nominal sun exposure. Unlike the other tetracycline antibiotics that can sometimes cause significant kidney damage, however, either can usually be safely used in patients with impaired renal function. All drugs in the the tetracycline family of antibiotics should never be taken or administered after the medications' expiration dates. Ingredients used in the manufacture of these medicines break down over time to form toxins that are particularly dangerous to the kidneys.

Secondary intracranial hypertension, a possible side effect of minocycline, is first indicated by a headache and dizziness.
Secondary intracranial hypertension, a possible side effect of minocycline, is first indicated by a headache and dizziness.

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Discussion Comments


I was prescribed doxycycline twice following tick bites: once as a preventative against Lyme Disease, after finding and removing an embedded tick, and the second time s for suspected early Lyme Disease. (Found no actual tick, but had "very suspicious" bug bite w. all the classic Lyme symptoms including bull's eye rash, fever and flu-like symptoms.) Both times I got extreme light sensitivity (from sunlight and computer, and extremely severe lasting headaches, very likely caused by the IH, (secondary) intracranial hypertension, this articles lists as a side-effect of minocycline (only). It's a possible side-effect of BOTH these drugs. (If you read pharmacy info. sheer or the FDA website drug description, you'll see HI listed also for doxycycline.

The first time I only had to take a single (22mg) dosage of doxycycline because the tick bite happened within 72 hours of my seeing my doctor and being able to take the meds. The second time this window had already closed, so I was put on a 20 day regime. I had to switch today (day three) to minocycline, and so far for me it feels better. Only time will tell if I can tolerate this "sister" drug. But I definitely could not tolerate the doxycycline. Probably everyone has such different sensitivities; you just have to fine and be guided by yours.


I have taken doxycycline for about 10 years to help manage a folliculitus outbreak. The doxycycline worked sometimes. I was taking 100mg twice per day. It became less and less effective over time. I started to double up my doses to see if that would have any affect and it worked some but never completely "cured" or "healed" my condition.

I have just started the minocycline and it seems more effective after three days. I can see a difference that I would feel only after taking doxycycline everyday for 40 days straight and not missing a dose. I guess I should follow up this post in about 30 days then another in 60 days. I monitor my medications very closely.

When you have had to live with a condition for ten plus years, it is a daily struggle. I will follow up this post in one month, then at month two. I hope this post helped someone.


I started on minocycline and had bad side effects! My dermatologist just switched me to Doxy. Anyone out there have any experience with whether or not it will cause yeast infections?


My grandfather suffered side effects from minocycline. He lives in a nursing home, and the attendants should have paid closer attention to what he was doing.

His nurse gives him his medication every day. She is supposed to know the side effects of each one and what to avoid.

On a sunny day, he asked her to roll his wheelchair up to the window and open it so he could get some sun. She did this without even thinking about his increased sun sensitivity due to the minocycline in his system.

She left him there for an hour while she went to lunch, and when she came back, he was bright red. His skin hurt, itched, and burned for a week because of her negligence.


@shell4life - My grandmother takes minocycline for her arthritis, and though she experienced a bit of dizziness and tiredness, she said it was a blessing in disguise. She has had trouble sleeping for years, but while she is on minocycline, she can fall asleep easily and get a good night’s rest.

The pain of her arthritis added to her insomnia. Minocycline has taken that pain away, so this also helps her sleep.

She does take it at night, though. I imagine if she took it in the daytime like your friends did, she couldn’t stay awake to do anything.


My kidneys don’t function as well as they should, so when I get urinary tract infections, my doctor gives me doxycycline. It always gets rid of the infection without any nasty side effects.

I don’t eat cheese or drink milk, so staying away from calcium-rich foods was not a problem for me. I don’t take supplements either, though I probably should to make up for the lack of calcium in my diet. However, I was an ideal candidate for doxycycline treatment.

Some of my friends have taken minocycline, and they say it’s way more intense than doxycycline. They told me that they got very dizzy and had to stay home from work while on it. Has anyone here had similar experiences with minocycline?


I have never taken minocycline, but my dermatologist did prescribe doxycycline to treat my acne. He said that it would control the bacteria that was causing my breakouts to worsen.

After my condition improved greatly, he told me that in his experience, doxycycline was the most effective treatment for acne in the dermatological community. Because its only side effective was sun sensitivity, I was able to take it for several months, and my face looked drastically different.

I will say that the sunburn precaution on the bottle is no joke. I went swimming in a lake while on the medication, and even though I had SPF 30 lotion all over my skin, I turned bright red.

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