Last updated on RxList: 5/24/2021
Bethkis Side Effects Center

What Is Bethkis?

Bethkis (tobramycin) is an aminoglycoside antibiotic used to treat cystic fibrosis patients with Pseudomonas aeruginosa. Bethkis is available in generic form.

What Are Side Effects of Bethkis?

Common side effects of Bethkis include:

Dosage for Bethkis

Bethkis should be taken twice daily by mouth in repeated cycles of 28 days on, followed by 28 days off.

What Drugs, Substances, or Supplements Interact with Bethkis?

Bethkis may interact with Edecrin (ethacrynic acid), Lasix (furosemide), urea, or mannitol. Bethkis should not be taken with drugs known to be toxic to structures within the ears, or drugs known to be toxic to nerves or nerve tissues.

Bethkis During Pregnancy and Breastfeeding

Bethkis may harm a fetus if taken while pregnant. Breastfeeding mothers should talk with their doctors to decide where to discontinue drug or continue breastfeeding.

Additional Information

Our Bethkis (tobramycin) Side Effects Drug Center provides a comprehensive view of available drug information on the potential side effects when taking this medication.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.


COPD (chronic obstructive pulmonary disease) is the same as adult-onset asthma. See Answer
Bethkis Consumer Information

Get emergency medical help if you have signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Call your doctor at once if you have:

  • new or worsening breathing problems, such as wheezing, cough, chest tightness, or trouble breathing;
  • hearing problems, ringing in your ears;
  • hoarse voice;
  • severe dizziness, spinning sensation, balance problems;
  • weak or shallow breathing;
  • muscle weakness; or
  • kidney problems--little or no urination, swelling in your feet or ankles, feeling tired or short of breath.

Common side effects may include:

  • cough, sore throat, hoarse voice;
  • feeling short of breath;
  • noisy breathing;
  • worsening of lung problems or cystic fibrosis;
  • coughing up mucus or blood;
  • altered sense of taste;
  • fever;
  • headache; or
  • rash.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Read the entire detailed patient monograph for Bethkis (Tobramycin Inhalation Solution)


COPD Foods to Boost Your Health - COPD Diet Tips See Slideshow
Bethkis Professional Information


Clinical Trials Experience

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in clinical trials of drugs cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice.

The data described below reflect exposure to BETHKIS in two placebo-controlled studies in 305 cystic fibrosis patients. Patients receiving BETHKIS ranged in age from 6 to 31 years.

In Study 1, an eight week study, 29 patients received BETHKIS versus 30 patients who received placebo for a total of four weeks on drug and four weeks off drug. All patients were ≤ 30 years of age (mean age 12.6 years) and 46% were females. 52.5% of patients were 6 to 12 years of age while 30.5% of patients were 13-17 years old. Only 16.5% of patients were adults (> 17 years old). Eighty percent (80%) of patients were chronically colonized with Pseudomonas aeruginosa while 20.3% of patients were initially or intermittently colonized with Pseudomonas aeruginosa during the study.

More patients in the placebo group discontinued/dropped out of Study 1 than in the BETHKIS group (23% [7/30] vs 3.4% [1/29], respectively). Five patients in the placebo group compared to none in the BETHKIS group discontinued/dropped out because of treatment-emergent adverse events (TEAEs) such as pulmonary exacerbations and respiratory disorders.

In Study 2, a 24 week study, 161 patients received BETHKIS versus 85 patients who received placebo in alternating four week on-off cycles for three cycles.

All patients were ≤ 46 years of age (mean age 14.8 years) and 45% were females. 41% of patients were 612 years old while 29% of patients were 13-17 years old. Only 30% were adults (>17 years). Eighty-seven percent (87%) of patients were chronically colonized with P. aeruginosa. Only 13% were either initially or intermittently colonized with P. aeruginosa during the study.

More patients in the placebo group discontinued/dropped out of Study 2 than in the BETHKIS group (9.4% [8/85] vs 4.3% [7/161], respectively). Of these, 3 patients in the BETHKIS group (1.9%) compared to 2 patients in the placebo group (2.4%) withdrew due to a TEAE. The most common TEAEs causing patients to discontinue from the study drug are respiratory, thoracic, and mediastinal disorders.

The most common adverse experiences reported were respiratory disorders, consistent with the underlying disease in the patient population being evaluated and these were similarly distributed between both BETHKIS- and placebo-treated patients. The following adverse reactions were reported in at least 5% of BETHKIS-treated patients and at rates ≥ 2% more common compared to the placebo-treated patients: decreased forced expiratory volume, rales, red blood cell sedimentation rate increased, and dysphonia (Table 1).

Table 1: Patients with Selected Treatment-Emergent Adverse Reactions Occurring in ≥ 2% of BETHKIS Patientss

Adverse Reactions BETHKIS
Forced expiratory volume decreased 59 (31%) 33 (29%)
Rales 36 (19%) 18 (16%)
Red blood cell sedimentation rate increased 16 (8%) 6 (5%)
Dysphonia 11 (6%) 2 (2%)
Wheezing 10 (5%) 4 (4%)
Epistaxis 6 (3%) 0
Pharyngolaryngeal pain 5 (3%) 2 (2%)
Bronchitis 5 (3%) 1 (1%)
Tonsillitis 4 (2%) 0
Diarrhea 3 (2%) 1 (1%)
Eosinophilia 3 (2%) 0
Immunoglobulins increased 3 (2%) 0

Postmarketing Experience

The following adverse reactions have been identified during postapproval use of tobramycin inhalation solution. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure.

Ear and labyrinth disorders: Hearing loss, Tinnitus [see WARNINGS AND PRECAUTIONS]

Skin and subcutaneous tissue disorders: Hypersensitivity, pruritus, urticaria, rash

Nervous system disorders: Aphonia, dysgeusia

Respiratory, thoracic, and mediastinal disorders: Bronchospasm [see WARNINGS AND PRECAUTIONS], oropharyngeal pain Metabolism and Nutrition Disorders: Decreased appetite


Drugs With Neurotoxic, Nephrotoxic, Or Ototoxic Potential

Concurrent and/or sequential use of BETHKIS with other drugs with neurotoxic, nephrotoxic, or ototoxic potential should be avoided.


Some diuretics can enhance aminoglycoside toxicity by altering antibiotic concentrations in serum and tissue. Therefore, BETHKIS should not be administered concomitantly with ethacrynic acid, furosemide, urea, or intravenous mannitol. The interaction between inhaled mannitol and BETHKIS has not been evaluated.

Read the entire FDA prescribing information for Bethkis (Tobramycin Inhalation Solution)

© Bethkis Patient Information is supplied by Cerner Multum, Inc. and Bethkis Consumer information is supplied by First Databank, Inc., used under license and subject to their respective copyrights.

Health Solutions From Our Sponsors