How long does it take for acyclovir to work

Acyclovir belongs to the antiviral family of medicines. Antivirals are prescribed by doctors to treat infections caused by viruses. Usually, antiviral medications work for certain groups of viral infections.

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What is Acyclovir?

Acyclovir is only accessible when prescribed by a doctor. The antiviral drug is widely used for the treatment of genital herpes, and herpes of the sex organs, brain, skin, and mucus membranes around the mouth and lips. Acyclovir is prescribed to treat widespread herpes zoster infections in newborns.

Acyclovir drug is effective in easing the symptoms of shingles and chickenpox. The medicine is also prescribed to prevent recurrent genital herpes. Though Acyclovir does not treat genital herpes or herpes infections completely, it significantly helps relieve discomfort and pain and increases healing.

Acyclovir is available in the form of a tablet, buccal tablets, cream, suspension, capsule, solution, or powder for solution. It is also available for injections that are used only in hospitals.

Your doctor may prescribe you Acyclovir to treat other virus-causing infections. However, the drug does not work for certain viral infections such as the common cold. Acyclovir tablets are also used as combination therapy. Your doctor may prescribe Acyclovir tablets with other medication.

Common uses of Acyclovir

Generally, doctors prescribe Acyclovir for the treatment of herpes viral infections including

  • Herpes simplex type 1 or HSV-1 initially causes oral herpes by may also contribute to genital herpes infections.
  • Herpes simplex type 2 or HSV-2 primarily causes genital herpes.
  • Varicella zoster, which causes chicken pox and shingles

Herpes Simplex Virus / Genital herpes

Commonly genital herpes occurs due to contact with HSV 2 or HSV 1 infected person. Herpes Simplex Virus 2 infections spread through sexual intercourse with people having genital herpes sore. 

Possibly, a person can get genital herpes infection from HSV 1 through oral sex with people having a cold sore.  The person may notice genital herpes symptoms 2-12 days after contact with the herpes zoster virus.

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Some common symptoms may include

  • Small red color bumps that burst to leave open sores around genitals, bottom, anus, or thighs.
  • Ulcers due to blisters rupturing
  • Pain, itching, or tenderness in the genital area
  • Scabs after the ulcers heal
  • Pain while urinating
  • Uncommon vaginal discharge

Once you get a genital herpes infection, it does not get completely healed with medication. It stays inside your body for a lifetime. The Acyclovir treatment can clear up symptoms, however, the virus lingers inside your body and can cause recurrent genital herpes in certain areas of your body.

Acyclovir tablets avert the symptoms from getting worse and shorten recurrent herpes outbreaks by 1 to 2 days. There are higher chances of successful treatment if you get Acyclovir as soon as you notice the symptoms.

If you are suffering from genital herpes and taking Acyclovir treatment, it can still pass to your sexual partner, so it is better to avoid sexual intercourse till you recover completely.

Cold sore/ cold sores

Cold sores are caused by HSV 1.  Primarily, you may experience an itch or tingle sensation before you notice blisters around your nose and lips. Till the blisters crust over and dry out, the infectious cold sores may expand through intimate contact such as kissing.

The common symptoms of a cold sore are tingling or itching around lips, a burning sensation around lips, fluid-filled small blisters that flare around and inside your mouth, and burst blisters leaving open sores that ultimately crust after the discharge dry out.

Once you get the infection, the virus resides in the nerve sheath for life. usually, the virus stays inactive and does not cause any symptoms, but it becomes active at certain time intervals causing a cold sore.

Generally, cold sores get better within 7 to 10 days without treatment. Acyclovir cream is used to treat cold sores and is an antiviral ointment that is available over the counter so you can buy it from pharmacies. Acyclovir treatment does not kill the virus but effectively prevents it from replicating, diminishing the harshness of symptoms.

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Chickenpox is caused by the varicella-zoster virus. The condition is infectious as early as 2 days before the spot appears, till the spots crust over. It takes around 5 days to crust over after they develop.

Usually chickenpox associated rash develops 10-21 days after contact with the virus. Some common symptoms of chickenpox include headache, fever, loss of appetite, fatigue, red or pink bumps that appear over several days, fluid-filled blisters that develop in a day and then break and leak, scabs that shelter the broken blisters and take several days to heal.

Typically, chickenpox in healthy children does not require treatment. For adults or children with the possible risk of complications due to chickenpox, the doctor may recommend acyclovir tablets to reduce the duration of infection and risk of associated complications. The varicella-zoster virus may get activated several years later and may cause shingles.


Shingles cause a blistering rash that sometimes can be painful. The rash appears because of the reactivation of the varicella virus that is responsible for causing chickenpox.

Just like the herpes zoster virus, once you get chickenpox, the varicella virus stays inactive in the nervous system.  The virus may get active again at certain time intervals, replicating and moving across the nerve fibers to the skin resulting in shingles.

Some common symptoms of shingles are your skin feeling sensitive to touch, burning or painful skin, a red rash developing after the pain feels, itching, fluid-filled blisters that rupture and crust over, headache, fatigue, and fever.

The symptoms of shingles may get better within a few weeks without treatment. Acyclovir medicine can significantly shorten the extent of an outbreak if you get it within 72 hours of symptoms developing.

How Acyclovir works

Acyclovir is an effective antiviral medicine. To get the maximum benefits, you should start treatment within 48 to 72 hours of the development of the first sign. Acyclovir treatment is most effective the sooner you start it.

Acyclovir is an antiviral medicine that possesses activity against herpes simplex virus type 1 and 2 and varicella-zoster virus. The antiviral medication act as a particular inhibitor of herpes virus DNA polymerase.

It is the main enzyme responsible for the lytic phase of infection by the herpes virus to encourage the multiplication of the virus. The activity against the herpes simplex virus is greater than against the varicella virus.

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How long Acyclovir takes to work

Taking Acyclovir oral suspension or tablet may take around 2 hours to reach the highest plasma concentrations.  The antiviral drug Acyclovir may take around 3 days to reduce the signs, however, the doctor recommends completing the recommended course of medication even if the condition feels better.

You may feel better within 1 to 3 days of taking Acyclovir. Acyclovir works remarkably when taken within 48 hours of the first time herpes outbreaks or you notice symptoms appearing in your body.

For zoster infections, acyclovir reduces the time it takes lesions to scab over, shortens the time required for rash healing, and reduces pain.  Adults over 50 years gain the best benefit by taking Acyclovir.

In the case of chicken pox, Acyclovir increases the healing, lessens the number of lesions and vesicles, and diminishes the rate of tiredness and fever by 2nd day.

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The antiviral medication, Acyclovir pointedly decreases the duration of acute infection and duration of lesion healing, in the case of genital herpes. Many patients reported decreased pain and new lesion formation after using Acyclovir.

When taken daily for 4 months to years, Acyclovir significantly reduced the severity and frequency of recurrent genital herpes in over 95% of people. Make sure you stick to your doctor’s orders to ensure the desired results of Acyclovir.

How to take Acyclovir tablets

The exact dosage and course duration of oral Acyclovir depends on the condition, age of the sufferer, the severity of the condition, other health issues, other medication you are presently taking, and your body’s response to the first dose of Acyclovir treatment.

Usually, for the first time genital herpes, the doctor may prescribe taking Aciclovir 200 mg 5 times a day or Acyclovir 400 mg  3 times a day for five days. For recurrent episodes, the healthcare provider prescribes 800 mg of Acyclovir 3 times a day for 2 days or 200 mg 5 times a day for five days.

Swallow the Acyclovir tablet with a glass full of water following your doctor’s instructions. Do not skip the dose of the recommended course. Make sure you take the usual dose on time and complete the course even if you feel better after a few doses.

In case you missed a dose or forget to take the usual dose, take it as soon as you realize. However, if you realize the missed dose at the time of the next dose, skip the missed dose and continue with the next one.

Patients with frequent recurrent episodes should use Acyclovir long-term as suppressive therapy to avoid outbreaks and diminish their frequency.

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Acyclovir and alcohol

It is ok to drink alcohol in a moderate amount while taking Acyclovir medication. Alcohol does not interfere with the way antiviral medicine work and Acyclovir still work effectively. However, if you have an infection, it is recommended not to drink alcohol for faster relief and to improve healing.

Acyclovir and pregnancy

Inform your healthcare provider if you are trying to conceive, pregnant, or breastfeeding to make sure that Acyclovir is safe for you and your baby. Usually, it is safe to take Acyclovir tablets or cream during pregnancy.

While taking oral Acyclovir, it may pass through the breast milk. Although it may not harm your baby while breastfeeding, still better to talk to your doctor and discuss the possible risks and if the benefits outweigh the risks included.

Side effects associated with Acyclovir

Some common but mild side effects of Acyclovir medicine include nausea, vomiting, fatigue, dizziness, headache, fever, abdominal pain, diarrhea, feeling faint, and skin reactions.

Some rare but severe side effects associated with Acyclovir include confusion, anemia, drowsiness, swelling below the skin, breath shortness, memory issues, hallucination, coordination problems, kidney problems, liver problems, seizure, and coma.

generally, children, seniors, and people with kidney problems, diabetes, seizures, heart disease, or diabetes are at higher risk of experiencing side effects of Acyclovir. People taking other medications which may cause drug interactions with Acyclovir may also experience side effects.

In case you experience any of these serious side effects or any allergic reaction while taking Acyclovir, seek emergency medical help.

Wrapping words

Acyclovir is an effective antiviral medicine that starts working within 24 to 48 hours after taking it. It is the most efficient if you take the medicine just after noticing the first symptoms in the body. Make sure you complete the prescribed course as recommended by your doctor and do not skip any dosage.