How long before the side effects wear off with using nitrofurantoin?

In the middle of the night I was sick w/ shakes, fever, chills & rapid heart rate, back to ER again being told my urine was clean. All labs and CAT scan were clear. They prescribed me a new antibiotic Cefpodoximine. 3 days on this I felt worse & did not sleep w/ racing heart & chest pain. Back to ER again where they said my urine was clean, but diagnosed me w/Trycardia
& all labs clean. They could not explain the Trycardia. Dr. Said stay on antibiotic & also added 100 mg of Macrobid & said to take both & when the Cefpodoximine was done continue Macrodid for a month. Meanwhile I was trying to hang on with my life to get into my infectious disease dr. I couldn’t get in till 12/18/18. I ended up in ER 3 times after the first course of Macrobid always assuming the shakes, chills, heart palpitations, chest pain, dizziness, muscle weakness and cold feet and sometimes hot and flushed all over were symptoms of the UTI not being resolved. I finally got in to my infectious disease DR. last Tuesday, who told me to get off the Macrobid because he wanted a clean urine sample & because I was leaving town for the holidays that I could go back on it after the urine sample was done. I would see him after the New Year. I stopped the Macrobid for 2 days & was so sick again assuming it was the unresolved UTI. I did my urine sample & immediately went back on it. Yesterday, I felt well all day except lower back pain & some random pain along my spine.
Before bed I went to the bathroom, my pee burned and I all of the sudden felt sick, my temp jumped to 99.9 and started w/ the shakes. Bad chest pain and tightness. My blood pressure jumped. I assumed it’s now a Kidney infection because of the back pain earlier in the day & I’ve been dealing w/ this for a month & again out of desperation went to ER. Where all labs, culture & Cat scan were clear. I knew chest pain was a side effect of Macrobid & was willing to deal w/ it to kill off the UTI. But after researching that the chest pain is actually a symptom of Pulmonary Toxcity and seeing some other people report similar symptoms w/ Macrobid I’m certain it’s been the Macrobid that has caused all the horrible symptoms I’ve dealt with. It seems the longer your on it the worse the side effects are and they linger even when your off it. I’ve delayed my Xmas vacation by a week hoping the side effects will be resolved.

Gastrointestinal: Sialadenitis, pancreatitis. There have been sporadic reports of pseudomembranous colitis with the use of nitrofurantoin. The onset of pseudomembranous colitis symptoms may occur during or after antimicrobial treatment. (See WARNINGS.)

Neurologic: Peripheral neuropathy, which may become severe or irreversible, has occurred. Fatalities have been reported. Conditions such as renal impairment (creatinine clearance under 60 mL per minute or clinically significant elevated serum creatinine), anemia, diabetes mellitus, electrolyte imbalance, vitamin B deficiency, and debilitating diseases may increase the possibility of peripheral neuropathy. (See WARNINGS.)

Asthenia, vertigo, and nystagmus also have been reported with the use of nitrofurantoin.

Benign intracranial hypertension (pseudotumor cerebri), confusion, depression, optic neuritis, and psychotic reactions have been reported rarely. Bulging fontanels, as a sign of benign intracranial hypertension in infants, have been reported rarely.

Respiratory
CHRONIC, SUBACUTE, OR ACUTE PULMONARY HYPERSENSITIVITY REACTIONS MAY OCCUR WITH THE USE OF NITROFURANTOIN.

CHRONIC PULMONARY REACTIONS GENERALLY OCCUR IN PATIENTS WHO HAVE RECEIVED CONTINUOUS TREATMENT FOR SIX MONTHS OR LONGER. MALAISE, DYSPNEA ON EXERTION, COUGH, AND ALTERED PULMONARY FUNCTION ARE COMMON MANIFESTATIONS WHICH CAN OCCUR INSIDIOUSLY. RADIOLOGIC AND HISTOLOGIC FINDINGS OF DIFFUSE INTERSTITIAL PNEUMONITIS OR FIBROSIS, OR BOTH, ARE ALSO COMMON MANIFESTATIONS OF THE CHRONIC PULMONARY REACTION. FEVER IS RARELY PROMINENT.

THE SEVERITY OF CHRONIC PULMONARY REACTIONS AND THEIR DEGREE OF RESOLUTION APPEAR TO BE RELATED TO THE DURATION OF THERAPY AFTER THE FIRST CLINICAL SIGNS APPEAR. PULMONARY FUNCTION MAY BE IMPAIRED PERMANENTLY, EVEN AFTER CESSATION OF THERAPY. THE RISK IS GREATER WHEN CHRONIC PULMONARY REACTIONS ARE NOT RECOGNIZED EARLY.

In subacute pulmonary reactions, fever and eosinophilia occur less often than in the acute form. Upon cessation of therapy, recovery may require several months. If the symptoms are not recognized as being drug-related and nitrofurantoin therapy is not stopped, the symptoms may become more severe.

Acute pulmonary reactions are commonly manifested by fever, chills, cough, chest pain, dyspnea, pulmonary infiltration with consolidation or pleural effusion on x-ray, and eosinophilia. Acute reactions usually occur within the first week of treatment and are reversible with cessation of therapy. Resolution often is dramatic. (See WARNINGS.)

Changes in EKG (e.g., non-specific ST/T wave changes, bundle branch block) have been reported in association with pulmonary reactions.

Cyanosis has been reported rarely.

Hepatic: Hepatic reactions, including hepatitis, cholestatic jaundice, chronic active hepatitis, and hepatic necrosis, occur rarely. (See WARNINGS.)

Allergic: Lupus-like syndrome associated with pulmonary reaction to nitrofurantoin has been reported. Also, angioedema; maculopapular, erythematous, or eczematous eruptions; anaphylaxis; arthralgia; myalgia; drug fever; and chills have been reported. Hypersensitivity reactions represent the most frequent spontaneously-reported adverse events in worldwide postmarketing experience with nitrofurantoin formulations.

Dermatologic: Exfoliative dermatitis and erythema multiforme (including Stevens-Johnson syndrome) have been reported rarely.

Hematologic: Cyanosis secondary to methemoglobinemia has been reported rarely.

Miscellaneous: As with other antimicrobial agents, superinfections caused by resistant organisms, e.g., Pseudomonas species or Candida species, can occur.

In clinical trials of Macrobid (nitrofurantoin) , the most frequent laboratory adverse events (1-5%), without regard to drug relationship, were as follows: eosinophilia, increased AST (SGOT), increased ALT (SGPT), decreased hemoglobin, increased serum phosphorus. The following laboratory adverse events also have been reported with the use of nitrofurantoin: glucose-6-phosphate dehydrogenase deficiency anemia (see WARNINGS), agranulocytosis, leukopenia, granulocytopenia, hemolytic anemia, thrombocytopenia, megaloblastic anemia. In most cases, these hematologic abnormalities resolved following cessation of therapy. Aplastic anemia has been reported rarely.

As far as how fast the side effects clear would depend on which ones you have. Most mild side effects should clear fairly quickly.