Seysara Side Effects: What to Expect and When to Call Your Doctor

One of Seysara's (sarecycline) main selling points compared to other tetracycline antibiotics is its favorable side effect profile. In clinical trials involving over 2,000 patients, Seysara demonstrated low rates of gastrointestinal, vestibular, and phototoxic side effects. That said, no medication is completely without risk. Here's a complete, honest breakdown of what to expect — and what to watch for.

Common Side Effects of Seysara

The most common side effect of Seysara — and the only one that occurred at a rate above 1% in clinical trials — is nausea. In pivotal Phase 3 trials, nausea occurred in 3.1% of Seysara users compared to 2.0% in the placebo group.

This is notably lower than the nausea rate associated with doxycycline, which can be significantly higher, especially if taken without food. If Seysara causes nausea, taking it with a light meal can help — though it can be taken with or without food.

Other side effects reported during clinical use (though less frequent) include:

Diarrhea

Vomiting

Abdominal pain

Vulvovaginal candidiasis (yeast infection) — due to antibiotic effect on normal flora

Mild sun sensitivity (less common than with doxycycline)

Serious Side Effects and Warnings — When to Call Your Doctor Immediately

While Seysara's serious side effects are rare, they can be severe. Know the warning signs and call your doctor or go to the emergency room if you experience:

Intracranial hypertension (pseudotumor cerebri): Symptoms include severe or worsening headaches, blurred vision, double vision, visual changes, or pain behind the eyes. This is more likely in overweight women of childbearing age. Stop Seysara immediately and seek medical care.

Severe diarrhea (possible C. difficile): Antibiotic-associated diarrhea — including C. diff colitis — can occur with any antibiotic. If you have bloody, watery, or severe diarrhea, even up to 2 months after stopping Seysara, call your doctor immediately. Do not take anti-diarrheal medication without consulting your provider.

Severe allergic reaction: Symptoms include difficulty breathing, severe rash, swelling of the face, throat, or tongue, or rapid heartbeat. Seek emergency medical care immediately.

Dizziness or vertigo: Like all tetracyclines, Seysara can cause lightheadedness or a spinning sensation. If this is significant, avoid driving or operating machinery and call your doctor. These symptoms usually resolve when the drug is stopped.

Signs of a secondary infection: Because Seysara is an antibiotic, it can occasionally allow other microorganisms (like fungi) to overgrow. Call your doctor if your skin infection worsens or if you develop unusual symptoms in the mouth, gut, or vaginal area.

Sun Sensitivity: What You Need to Know

Seysara can increase your skin's sensitivity to sunlight — a side effect shared with all tetracycline antibiotics. While Seysara causes less photosensitivity than doxycycline in clinical studies, it's still important to:

Apply broad-spectrum sunscreen (SPF 30 or higher) daily

Wear protective clothing when outdoors for extended periods

Avoid tanning beds and prolonged sun exposure during the course of treatment

Special Warnings: Pregnancy, Fertility, and Children

Seysara carries important warnings for specific populations:

Pregnancy: Do NOT take Seysara if you are pregnant or may become pregnant. It can cause skeletal malformations in the developing fetus and permanent tooth discoloration in children. If you become pregnant while taking Seysara, stop immediately and contact your doctor.

Breastfeeding: Seysara passes into breast milk and is not recommended while breastfeeding.

Male fertility: Animal studies suggest Seysara may affect sperm. Men trying to conceive should discuss this risk with their doctor before starting Seysara.

Children under 8: Tetracycline-class antibiotics are not recommended for children under 8 due to permanent tooth discoloration and bone growth effects. Seysara is approved only for patients 9 and older.

How Seysara's Side Effect Profile Compares to Alternatives

Compared to doxycycline, Seysara causes less photosensitivity and GI distress. Compared to minocycline, Seysara has a much lower risk of vestibular side effects (vertigo, dizziness), pigmentation, and autoimmune reactions. Its narrow spectrum also means less disruption to gut bacteria. To learn about specific drug interactions to be aware of, see our guide on Seysara drug interactions